The Ultimate SEO Glossary

Are you new to the world of search engine optimisation and just come across a new term, accronym or... something, and don't know what it means? Well help is at hand in the form of our Ultimate SEO Glossary, a complete guide to every term you might happen to come across.

Don't know your 301 redirects from your 302s? Think a crawl error is when a baby bumps into a door? Read on...

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200 OK - the standard response for successful HTTP requests.

301 Moved Permanently - redirect this HTTP request to the given URI.

302 Found - the requested resource has been temporarily moved a new URI.

400 Bad Request - the HTTP request has an invalid syntax.

401 Unauthorized - The user is trying to access something that has not been authenticated.

403 Forbidden - the server is refusing to serve a request. This could be because of the removal of a file permission or a restriction based on an IP Address.

404 Not Found - the server was unable to locate anything matching the requested URI. This usually implies the page does not exist anymore.

500 Internal Server Error - an error message that displays when an issue was found locating a resource (like a web page), but no more information is available.

502 Error - the server is a gateway or proxy server, and it is not receiving a valid response.

503 Error - the webpage or service is unavailable due to overload or maintenance.

504 Gateway Timeout Error - this usually implies that the server that is trying to be accessed is down or under maintenance. It's an HTTP error that means one server did not receive a timely response from the other.

803 Crawl Error - an incomplete HTTP response received.


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Above the Fold – content that can be seen before scrolling down on an email or web page.

AdSense – the contextual advertising network from Google that offers a scalable automated ad revenue stream.

Ahrefs – backlink checker & SEO reporting tool.

Alexa - Owned by, Alexa is a search service which allows you to measure website traffic. It is free to use, though not considered to be one of the more accurate tools available.

Algorithm – a program that is used by a search engine to determine what to present to a user making a search query.

ALT text/tag or attribute – the text description of an image that loads when the image itself does not render for any reason.

Analytics – ways of measuring and analysing data about website usage.

Anchor text – the text that is used to link to a web page. It shows to search engines and page visitors’ details as to what the page being linked to is about.

Application Program Interface (API) - conventions or routines used to access various software functions.

Ask - a search engine that is owned by InterActive Corp, known as Ask Jeeves until 2006.

Asynchronous Javascript and XML (AJAX) - allows a web page to request additional data from the server without requiring a whole new page to load, cutting down on page load speed

Authority - the authority of a website determines how likely it is to rank well in search engines. Authority is most closely associated with the quality of the backlink profile and the link equity derived from it; site age; traffic trends; site history; and the quality of the site’s content.


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Backlink – a link that is coming into a website from another site.

Backlink profile - a website's profile based on backlink data, a good link profile will contain no spam links.

Baidu - the leading Chinese search engine.

Bing – Microsoft’s search engine.

Bing Webmaster Tools – Bing’s website optimisation tool.

Black hat SEO – certain marketing techniques that are considered deceptive by search engines.

Blog – an online journal normally presented in reverse chronological order. Most blogs use a content management system such as WordPress rather than being a standalone website. A truncation of the expression, weblog.

Blog comment spam - comments that are left on a blog that add no value to the article or discussion, typically including a backlink to an external website. Blog comment spam may be automated by a bot or left manually.

Blogger – someone who publishes a blog. Also the name of Google’s blogging platform.

Blogroll - a list of external links on a website or blog to other blogs that may be associated with the company or blogger. Although once a popular linking method, blogroll links are no longer considered favourably by Google.

Bold - see Strong tag.

Boolean search – a type of search that combines keywords and operators like ‘NOT’, ‘AND’, ‘OR’, etc to produce better results.

Bot – a program that carries out autonomous tasks. Bots are often used by search engines to find web pages and add them to search indexes.

Bounce rate – the percentage of visitors who arrive on a web page and then leave the site without visiting any other pages.

Brand - a company’s brand represents its values and what it means to consumers.

Branded keywords – keywords that people use to type into a search engine, that are associated with your brand or business. E.g. Nike, Reebok, Coca-Cola.

Breadcrumb navigation – navigation that allows a user to see where they are on a site.

Brin, Sergey - co-founder of Google.

Broken link - a hyperlink that is incorrect or pointing to a webpage that no longer exists. A broken link will typically return a 404 Not Found error page.

Broken link building - finding broken links and contacting webmasters to replace them with links to similar content on your site. See ‘link building’.

Browser - the client/interface used to access the web, for example Google Chrome.

Buyer’s journey – the steps that consumers go through before purchasing (awareness, consideration, decision). See The Buyer’s Journey Explained.

BuzzStream - a platform designed to manage your influencer outreach efforts. It discovers contact information, social media profiles and website metrics for you, while also keeping track of all the conversations you have with your influencers.


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Cache – a component that stores data so any future requests to see the information can load faster. Has several variations such as browser cache - information stored in a web browse.

Cannibalisation – cannibalisation refers to the targeting of the same keyword, term or phrase on multiple pages of your website, or group of websites. See ‘Semantic Flux’.

Cascading Style Sheets (CSS) – the code part that defines how various elements of the website look.

Chrome – Google’s web browser.

Citations - an online listing that contains your business's name, address and phone number (known as NAP). An important ranking signal for local SEO. More information can be found in these listings such as business description, reviews, email address, fax, etc. Also known as a directory listing.

Citation flow - a score between 0-100 on how influential a website might be based on the number of links pointing to it.

Click-Through Rate (CTR) – the percentage of people who click on an advertisement or listing.

Client - a computer, piece of software or process that makes requests for information from other computers, programs or processes.

Cloaking – a technique of showing different content to search engines than the people who are searching. Often this is considered a ‘black hat SEO’ technique, depending on how it is being used.

Clustering - the organising of search results when multiple listings appear for one website. Clustering also refers to the way search engines group different authorities on a certain topic together, showing their relationship.

Co-citation - if two links are near to each other on a web page they may be considered to be related. This is determined by a topical authority based search algorithm. When words appear near each other, latent semantic indexing deems those to be related.

Comment system – the way that users can leave feedback on a blog.

Conceptual links - some of the more advanced search engines are attempting to understand links beyond focusing on the anchor text, for example by using co-citation.

Content Management System (CMS) – a way of adding information to a website and updating information already on a website.

Content marketing – using content to attract customers (creating, sharing etc).

Conversion – when a user completes a desired goal (for example, purchase, feedback, signing up for a newsletter).

Conversion rate – the percentage of users who carry out a conversion.

Conversion rate optimisation (CRO) – a way of improving the conversion rate of a website.

Cookie – a data file that is deposited onto the computer of a user to track their movements.

Crawler - see Web crawler.

Crawl depth - how many pages of a website has been crawled, including those pages deep within the site’s structure. Link equity helps a website to be crawled more deeply.

Crawl frequency - how often a website is crawled by the Google Spiders. Well trusted and frequently updated websites may be crawled more often.

Canonical URL - If there are multiple versions of a web page or piece of content, the canonical URL tells the search engines which is the original version that should be added to their index and display in SERPs. The non-canonical versions of the URL will also pass all of their authority to the canonical URL.

Cutts, Matt - Head of Web Spam at Google, currently on sabbatical indefinitely.


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Dead link - a link that points to a page that no longer exists.

Dedicated server - more reliable than shared servers, a dedicated server looks after just one website, or a small collection of sites.

Deep link - a link pointing to an internal page within a website.

Deep link ratio - the ratio of links that point to internal pages versus the overall website.

Directory – like a digital phone book - except this is a directory of websites (for example Yahoo!).

Directory listing - see Citations.

Disavow - the disavow tool is available in the Google Search Console, and allows webmasters to state that they do not wish to be associated with websites that have previously linked to them.

DMOZ - The Open Directory Project

Domain – the main web address of a website.

Domain Authority - a score marked out of 100 that is developed by Moz. It predicts how well a website will perform on search engines.

Domain Name Server/System (DNS) - a naming scheme mechanism used to help resolve a domain or host name to a specific TCP/IP address.

Doorway page – a page that is specifically created to attract search engine traffic. Often seen as a black hat SEO tactic.

DuckDuckGo - a search engine, unique in that is does not retain any user data.

Duplicate content – the content of a web page which is the same, or overly similar, to that on another web page. This kind of content isn’t viewed positively by search engines.

Dwell time - the length of time a user spends on a website before returning to the search results page.

Dynamic content - an element of a website that changes/adapts depending on the preferences of the user, creating a customised experience.


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Editorial link - these are links on websites where some level of editorial control has been exercised.

Engagement metrics – a way of measuring how users are interacting with a piece of content.

Everflux - the term used by Google to describe the constant updating of their search index.

Exact match anchor text - the term used when the anchor text of a backlink or internal link exactly matches the keyword or phrase the linked to page is hoping to rank for.

External Link – see Backlink.


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File transfer protocol (FTP) - a method used to transfer data between computers. FTP capabilities are included in most content management systems and blogging platforms.

Firefox – an open source web browser.

Flash – graphics based animation software that used to be very popular. Search engine’s were unable to read flash websites and thus their popularity has reduced.

Fold – the point of a website that gets cut off by the screen or browser window.

Follow - a command on a website that instructs bots to follow either any of the links on a page or a specific link. Links are generally follow by default. The opposite of Nofollow.

Frames - an old website development technique created by Netscape which is used to display multiple pages on a single display. Frames makes it difficult to deep link to content, while modern content management systems and dynamic languages mean they are now redundant.


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Goals – used in Google Analytics as a measurement of a specific website interaction (purchase, enquiry etc).

Google – market leading search engine.

Google+ - Google’s social network.

Google Analytics – market leading website statistical analysis tool that help you understand your site’s performance.

Google bombing - a black hat SEO technique, Google bombing involves pointing hundreds, or even thousands, of links to a page in order to get it ranking well for a specific search query.

Googlebot – Google’s web crawler.

Google Checkout – a payment service provided by Google.

Google Keyword Planner – a tool provided by the search engine within Google AdWords that can be used to estimate keyword competition and recommend keywords to use.

Google Tag Manager - Google’s tag management system for websites and mobile applications.

Google Trends – a tool that shows the volume of searches for specific keywords.

Google Search Console - previously known as Google Webmaster Tools, a tool that allows you to monitor your site’s appearance in Google search.

Google Sitemaps - used by webmasters to help Google index all of the content on their website.

Google Sitelinks - for search listings that Google considers to be a good authority on a particular subject, multiple deeper links may be presented below the main link.

Google Trends - shows how search volumes for a particular keyword change over time.

Google Webmaster Guidelines - a list of guidelines that Google issues to webmasters to ensure they provide the best experience for their users and avoid incurring a penalty.

Google Webmaster Tools - see Google Search Console.

Grey hat SEO - refers to SEO methods that may sometimes violate Google’s Webmaster Guidelines or typical ethical standards, but does not have the malicious intent of typical black hat methods.


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.htaccess - an Apache directory-level configuration file that is used to redirect files or protect passwords.

Headings – the website text that sits inside the heading tags (H1, H2 etc).

Headline - the title of a story or blog post.

Hidden text – this is an SEO technique that is used to show search engines what users don’t see. Considered a black hat SEO tactic.

Hummingbird algorithm update - implemented to enable improved conversational searches on Google.

Hit – colloquialism for a user visiting a website.

HyperText Transfer Protocol (HTTP) – the protocol used most often for communication between servers and web browsers.

HyperText Markup Language (HTML) – the language used to create web pages.


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Inbound link – a hyperlink to a specific web page that directs traffic to that page and is from an outside website. See Backlink.

Index – a search engine’s library of web pages.

Indexed – refers to when a site has been added to a search engine’s index.

Indexed pages – the pages of a website that are stored by a search engine.

Information architecture - refers to the design, categorisation, organisation and structure of website content in a logical way.

Internal link – a link from one web page to another inside the same website.

Internet Explorer – Microsoft’s web browser.

Internet Protocol (IP) address – the IP Address is the identifying address of a computer connected to the Internet.

Internet Service Provider (ISP) - provide end users with internet access, for example Virgin Media, Sky and BT.

Instant Answer - an answer to a search query provided in the search engine results page, meaning the user may not have to click through to see the information they need.

Invisible web – the information on the web that hasn’t been indexed by a search engine.

Inbound marketing - the process of providing the information that the buyer is looking for, at the right time, and then nurturing them down the buyer’s funnel.


JavaScript – language that is embedded into HTML to add dynamic features.

Joomla - popular open-source content management system.


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Keyphrase - see keyword.

Keyword – a word or phrase that is used to search online via a search engine.

Keyword density – the percentage of the content on a page that contains a specific keyword. Used to be an important metric for SEO but is now largely ignored.

Keyword not provided - When searching for organic referral traffic in Google Analytics, ‘not provided’ appears in place of the actual keywords searchers came through on. This occurred after Google shifted to secured search.

Keyword research – the process of finding the right keywords to use on your web pages.

Keyword research tools - platforms which help you to discover which keywords you should be targeting based on search volumes and search trends. The most commonly used is Google AdWords Keyword Planner.

Keyword stuffing – using too many keywords on one or many pages i.e. where keyword density is too high.

Knowledge Graph - a knowledge base owned by Google, used to enhance search results with more detailed information - see ‘Instant Answer’.

Kerboo - formerly known as LinkRisk, Kerboo is a suite of digital tools designed to make digital tasks more efficient and marketing decisions better informed.


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Landing page – the page where a user arrives on a website after clicking through from an ad or link.

Link – a citation between web documents that connects them. Search engines usually view links between websites as a vote of trust.

Link atrophy - the loss of backlinks to your website over time.

Link bait – a page that has a specific purpose of attracting incoming links from social media etc.

Link building – working to cultivate incoming links to your site.

Link bursts - a sudden increase in the quantity of links pointing at a website.

Link churn - see Link atrophy.

Link equity - a website’s link equity is decided by its link popularity and the authority of the sites linking back.

Link farm – a group of websites that are all linking to each other. Seen as a black hat SEO tactic.

Link popularity - your link popularity is determined by the number of links pointing to your website.

Link profile – see Backlink profile.

Link reputation - a combination of your link equity and anchor text determines the link reputation.

Link text – the text of a link that is visible to a user. See ‘anchor text’.

Link velocity - the rate a website, or page of a website, gains new inbound links.

Local SEO - optimising the appearance of a business in local search results.

Long tail – a longer and more specific search query. These are usually uncommon and searched less frequently.

Log file - a file output from a web server containing a record of all requests (or ‘hits’) that the server receives.

Log file analysis - used to understand search engine crawl behaviour on a website, conducted when carrying out website SEO audits.

Link intersect - an application within the Moz Pro and Ahrefs suite of SEO tools used to identify which inbound linking domains have two or more websites have in common.


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Majestic – website backlink analyzer.

Manual penalty – a potential penalty from Google for violating its guidelines.

Manual review - all of the major search engines complement their algorithms with a manual review process that is used to identify web spam as well as improve their relevancy algorithms.

Meta description – provides a summary of the content of the web page. Appears below the Meta Title Tag on a search engine results page.

Meta keywords – these used to be used by search engines to establish what a site was about but they are now redundant.

Meta title – an HTML meta tag that describes a specific web page and often forms the blue linking phrase found on search engine results pages. Should contain keywords associated with the page. Also known as the page title or meta title.

Metric – a measurement that is used by analytics programs to analyse a website performance.

Mirror site - used to duplicate (or mirror) the content of another website.

Moz – SEO software.

Moz Local - generates, as well as maintains, business listings across the websites, directories and apps that matter most for local search.


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Navigation – a way of helping users of a website to see where they are and how to get to where they want to go.

Negative SEO - the use of black hat SEO techniques to negatively affect the rankings of a third-party website, perhaps that of a competing company. This might involve Google bombing in an attempt to get the website penalised.

Nofollow – a command on a website that instructs bots not to follow either any of the links on a page or a specific link. The opposite of Follow.

Noindex – a command on a website that instructs bots not to index a page or specific link.

Non-reciprocal link – where one site links to another but that site does not link back.

Non-branded keywords - any word or phrased used for online searches that do not include a brand or company name.


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Open Site Explorer - an application within the Moz Pro suite of SEO tools used to conduct link research and analyse backlink profiles.

Opera - a fast, standards-based web browser.

Organic link – those links that are published by a web master because they are considered to have value for users.

Organic search results - these are the search listings that are displayed in an order based on Google’s search algorithm. They sit below the paid listings at the top of the search engine results pages (SERPs).

Orphaned link - see Broken link.

Outbound link - these are links that you make from your website to an external website,


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Page, Larry - co-founder of Google.

PageRank – a value assigned by the Google algorithm to a page. The value is between 0 and 10 and is based on factors like trust and popularity. Google’s algorithm has now moved away from PageRank, no longer updating it.

Page load speed - the time it takes for a browser to download the first byte from a web server.

Page title – see Meta Title.

Page Authority - a score marked out of 100 that is developed by Moz. It predicts how well a specific page will rank on search engines.

Paid inclusion - if a website passes editorial quality guidelines it can buy relevant exposure through paid inclusion. Directories such as Yahoo! Directory and allow websites to do this.

Panda algorithm update - the first of the big Google updates, Panda categorises websites into buckets based on their perceived quality.

Pay-per-click advertising (PPC) - most search ads and contextual ad programs are sold through the PPC model. The advertiser is not charged for space or views, but rather every time a user clicks on an ad.

Penalty – where search engines prevent websites that are suspected of spamming from ranking highly in search results.

Penguin algorithm update - a Google update designed to penalise websites that have an unnatural link profile.

Personalisation - refers to the unique search results pages users see depending on their location, search history or other relevant personal factors.

PHP - an open source server side scripting language used to render web pages or to add interactivity to them.

Pigeon algorithm update - a Google update to local search which brought it into line with more signals typically associated with general web search.

Piracy algorithm update - an update which targeted websites (excluding Blogspot and YouTube) which had an excessive number of DMCA takedown requests.

Private Blog Network - A private blog network (PBN) is a set of domains that you or another individual owns in the attempt to create backlinks to your sites. It is considered a grey/black hat SEO method.


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Quality content - somewhat subjective, but quality content would be considered to be unique and worth linking to by relevant websites.

Quality link - an inbound link that is from a website that is relevant and that has a high domain authority. Other characteristics of a quality link might be how old the linking website is, how hard the link is to get and if the link comes from within a piece of content.

Query – see Search Query.

Query refinement - a manual and automatic process used to refine a searcher’s results based on how useful they found previous results.


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Rankbrain - Google's machine-learning artificial intelligence that is used to help process and rank search results.

Reciprocal link – where two sites link to each other.

Redirect – methods that are used to change the final destination of a link and the address of a landing page. See 301 and 302.

Referrer - where a visitor came from, i.e. a search engine or linking domain.

Referring IP – an IP address which hosts one or more websites that contain links pointing to a given URL or domain.

Reinclusion - a request a webmaster makes to a search engine following a penalty.

Relative link - a link which shows a relative link path within the tag, rather than the entire reference URL (absolute link). Canonicalisation and hijacking issues mean that absolute links are preferable to relative links.

rel="canonical" - see Canonical link.

Relevancy - how useful a searcher finds a particular result.

Return On Investment (ROI) – analysing and quantifying whether investment spend is producing justifiable results.

Robots.txt - a protocol used by websites to communicate with web crawlers and bots. Often used to determine which sections of website can be crawled by a search engine’s bots.

Root domain - The overall structure of a web property stems from the root domain. E.g.


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Safari – Apple’s web browser.

Schema - microdata that helps search engines to interpret the content on your website. Search engines use schema to serve relevant results to users.

Screaming Frog - an SEO Spider. It allows you to crawl, analyse and audit a site from an onsite SEO perspective.

Search engine – a program that searches documents online for matches to keywords that have been entered by a user.

Search engine marketing (SEM) - also known as search marketing, SEM incorporates SEO and content marketing to help websites rank in the search engine results pages.

Search engine optimisation (SEO) – increasing the number of people visiting a website by boosting the site’s search engine ranking.

Search history – data on searches carried out, which can be used for better targeting.

Searchmetrics – SEO software.

Search query - a keyword or phrase inputted into a search engine.

SEO copywriting - writing online content in such a way that makes it easier to be found by search engines.

SERP – acronym for search engine results page.

Server - a computer where web files are hosted, as well as used to serve them to the web.

Server logs - hosted on servers, these logs record website traffic sources and trends.

Semantic Flux - when groups of interrelated domains compete (intentionally, or unintentionally) for the same keyword or phrase.

Site map – a structured group of pages, or a single page, that links to all the user accessible pages on a website. Is often in either HTML or XML format

Social media – referring to online platforms, such as Twitter and Facebook, where different forms of content are shared by users and brands.

Spam – unsolicited messages.

Spider – see Web crawler.

Splash page – a page that may have animated graphics but no relevant text content.

Static content - content on a website that does no

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