Technical SEO Glossary - Definitions for Common Terms

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Accessibility

Accessibility refers to how easy it is for people that use screen readers and other disability aids to access a website. Deque's axe library is a set of recognized standards that website owners and SEOs can use to improve website accessibility. You can review how accessible your website is by using a website accessibility audit tool.

ALT Text

Stands for “alternative text”. When supplied with an image, ALT text tells people using screen readers what is being shown in that image. It also helps bots to understand what is in that image.

AMP

AMP is an open-source library that is designed to produce fast-loading pages that are optimized for mobile. You can learn more in our AMP Hints section.

Anchor Text

Anchor text is the text that contains a link to another web page, either internal or external. It is advised that anchor text is keyword-rich and describes the page to which it’s pointing.

Backlinks

Backlinks are links from other websites to your website. Backlinks are one of the most important ranking factors for search engines. The more high-quality backlinks you have, the higher your website will rank in search results. You can review your backlinks by using a website link crawler.

Bot/Crawler

Crawlers or “bots” are programs search engines use to crawl websites, which is the first step in the process of indexing and ranking content for search engine results pages. Google’s crawler is called “Googlebot”, while Bing’s is “Bingbot”. It’s useful to know the names of different bots in order to provide them with directives in your site’s robots.txt file.

Canonical Tag

A canonical tag ("rel canonical") is applied to the <head> of pages to show search engines that there’s another page, a specific URL, that should be considered the master version. Canonical tags need to be correctly applied, as they can cause major indexing issues if they are not. See also: Indexability

Chromium

Chromium is the open-source browser project that underpins Google Chrome (and several other browsers). In technical SEO, it's relevant because most crawlers — including Sitebulb — use Chromium to render JavaScript-heavy pages the same way a real browser would. See also Headless Chromium.

Core Web Vitals

Core Web Vitals are a set of metrics that measure the performance of a web page related to user experience. Core Web Vitals include Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS). Google considers Core Web Vitals to be an important ranking factor. These can be checked by performing a website performance audit. See also: Performance

Cloud Crawler

A cloud crawler, or web-based crawler, is a tool that allows SEOs to run website audits online, without needing to download software to their machine.

Content Delivery Network (CDN)

A CDN is a network of servers distributed across multiple locations that delivers web content from a server geographically closer to the user, reducing load times. Using a CDN is a common recommendation for improving page speed. See also: Page Speed/Page Load

Crawl Budget

Crawl budget is the amount of time and resource Googlebot (or any search engine bot) allocates to crawling a given website. Sites with crawl budget issues may have important pages missed or recrawled infrequently, particularly on very large sites. See also: Bot/Crawler, Indexing

Crawl Depth / Crawlability

Crawl depth refers to how many clicks it takes a crawler to reach a page from the homepage; crawlability describes how easily a bot can access and crawl a website overall. Pages buried too deep in a site's structure are at greater risk of being crawled less often, or not indexed. See also: Indexability, Internal Links

CSS

Stands for Cascading Style Sheets. CSS is a type of code used for specifying the presentation and styling of a document written in a markup language such as HTML.

Dofollow Link

Dofollow links are links with a rel=”dofollow” HTML tag applied to them. This is an instruction to search engine crawlers and other bots to follow, i.e. crawl, that URL. Dofollow links are the most desirable and powerful in terms of transferring link equity. See also: Nofollow links

DOM

Stands for Document Object Model (DOM). The DOM is a programming interface for web pages. It represents the page so that programs can change the document structure, style, and content.

Duplicate Content

Duplicate content is an issue that can be flagged in technical SEO audits when the website audit software finds two or more pieces of content it considers to be the same. Find out more in our guide to duplicate content.

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External Links

External links are links on your website that link to other domains. External linking can help to improve the authority of your website, but it's important to only link to high-quality websites. See also: Internal Links

Headless Chromium

Headless Chromium is a version of Chromium that runs without a visible user interface, typically used by crawlers and testing tools to render and process pages programmatically. Sitebulb uses headless Chromium to render JavaScript when auditing sites, letting it see pages the way a browser (and Googlebot) does. See also: Chromium, Rendering (client side and browser side)

Hreflang

Hreflang is an attribute that specifies the language and geographic suggestions for a web page. Hreflang attributes are used when more than one version of a page exists, to help search engines serve the right version based on users' location and language. Learn more in Sitebulb’s international Hints section or try out our Hreflang Checker.

HTML

Stands for HyperText Markup Language. HTML is the standard code for documents designed to be displayed in a web browser. It defines the content and structure of web content.

HTML Sitemap

HTML sitemaps are sometimes created to make website navigation easier for your visitors. Often available in the footer, it’s a file that lists every page on your website. This is different to an XML Sitemap.

HTTPS

Stands for Hypertext Transfer Protocol Secure. HTTPS is a secure version of HTTP that encrypts communication between a web server and a web browser. HTTPS is important for SEO because Google gives a ranking boost to websites that use HTTPS. See also: Security

Find out more in our Sitebulb security Hints section or go right ahead and run a Website Security Audit.

HTTP Status Codes / 404 Errors

HTTP status codes are three-digit codes a server returns in response to a browser or crawler request, indicating whether it succeeded (200), redirected (3xx), or failed (4xx/5xx). A 404 status code means "page not found" — the requested URL doesn't exist on the server. See also: Redirect

Indexability

Indexability is the term used to describe a web page’s ability to be indexed by search engines, which is essential in order to be ranked in results pages. A crawler like Sitebulb can be used to check website indexability.

Indexing

Indexing refers to the process a search engine crawler/bot performs to process and organize web pages. Search engines must crawl web pages before they can put them in the queue to be indexed, and only indexed pages can be ranked to appear in search engine results pages.

Internal Links

Internal links are links going from one web page to another web page on the same domain. Internal linking helps search engines to understand the structure of your website and to find all of your important pages. Find out how to do a link audit here. See also: External Links

JavaScript

JavaScript is a type of code used to bring web pages to life. It allows developers to create dynamically updating content, use animations, pop-up menus, clickable buttons, control multimedia, and more for interactivity.

While JavaScript can be beneficial for creating engaging content, it can cause issues for SEO. Google does process and render JS as part of its indexing process. However, ensuring that key page content and information is part of your HTML response is essential for SEO. Learn more: JavaScript SEO Resources

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Keyword Cannibalization

Keyword cannibalization happens when multiple pages on the same website target the same keyword or search intent, causing them to compete against each other in search results rather than one page ranking strongly. See also: On-page Optimization

Lazy Loading

Lazy loading is a technique where images or other resources only load when they're about to enter the user's viewport, rather than all at once. It can improve page speed, but if implemented incorrectly it can prevent search engines from seeing lazy-loaded content. See also: Page Speed/Page Load, JavaScript

Link Equity

Link equity is the term used to describe the value or authority passed via a link from one page to another.

Log File Analysis

Log file analysis is the practice of examining a website's server logs to see exactly how search engine bots have crawled a site: which URLs were requested, how often, and what response was returned. It's one of the few ways to see actual bot behavior, rather than inferring it. See also: Bot/Crawler

Metadata

Metadata is data about data. In the context of SEO, metadata about a web page includes the title tag, meta description, meta robots tags, structured data, header, and image tags. Metadata helps search engines understand the content and structure of the web page.

Meta Description

The meta description is an HTML tag that provides a brief summary of a page's content, shown (though not always used) as the snippet under the title tag in search results. It doesn't directly affect rankings but can influence click-through rate. See also: Metadata, Title Tag

Meta Robots Tag / Noindex

The meta robots tag is a snippet of HTML placed in the <head> of a page that gives instructions to search engine crawlers, such as "noindex" (don't index this page) or "nofollow" (don't follow links on this page). It works at the page level, unlike robots.txt, which works at the site/folder level. See also: Robots.txt, Indexability

Mobile-First Indexing

Mobile-first indexing is Google's practice of using the mobile version of a website's content for indexing and ranking, rather than the desktop version. It means the mobile version of a page needs to contain everything you want Google to see. Learn more in Sitebulb's mobile-friendly Hints section. See also: Mobile-Friendly

Mobile-Friendly

In technical SEO, mobile-friendly refers to the need for websites to align with Google’s mobile-first indexing strategy in response to the enormous growth of mobile traffic (in comparison to desktop). Learn more in Sitebulb’s mobile-friendly Hints section.

Nofollow Link

Nofollow links are links with a rel=”nofollow” HTML tag applied to them. The nofollow tag tells search engines to ignore that link. While they do not transfer link equity, they can still drive traffic and therefore have some SEO value. See also: Dofollow Links

On-page Optimization

On-page optimization is the process of applying SEO best practices to web page content and metadata to improve its chances of ranking for specific search terms. Check out Sitebulb’s on-page SEO analysis functionality here.

Orphan Pages

Orphan pages are pages that exist on a website but have no internal links pointing to them, making them difficult (or impossible) for crawlers and users to find via normal navigation. You can find orphan pages using Sitebulb's Internal Hints section. See also: Internal Links

Page Speed/Page Load

The speed at which a web page loads. Page speed is an important ranking factor for search engines. There are a number of things you can do to improve your page speed, such as optimizing your images, compressing your files, and using a content delivery network (CDN).

Pagination

Pagination is the practice of splitting a long list of content (such as products or blog posts) across multiple numbered pages. Search engines need to be able to crawl through paginated pages to discover all the content, so pagination needs to be implemented carefully. See also: Crawl Depth/Crawlability

Parse a Response

Parsing a response is the process a crawler uses to read and extract information — such as links, canonical tags, and content — directly from the raw HTML a server returns, before any JavaScript executes. This differs from rendering, where the page's JavaScript is processed to build the final, visual version of the content. See Sitebulb's guide comparing response and rendered HTML for more. See also: Rendering (client side and browser side)

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Redirect

A redirect is when users and bots are sent immediately from one URL to another URL. There are two main types of redirects: permanent (301 status) or temporary (302 status). You can find out how to find and fix 301 redirects here as well as more general information in Sitebulb’s redirects Hints section.

Redirect Loop

A redirect loop is when a page redirects to another page that immediately or eventually redirects back to the original URL. Learn more in Sitebulb’s redirects Hints section.

Rendering (client side and browser side)

Rendering is the process through which the page code and resources like Java Script are processed and executed to build the final, visual version of the page content. There is “client side” or browser rendering (performed by the browser being used to access the web page) and there is “server side” rendering (performed by the server that stores the web page data).

Google is doing more and more client side rendering, and there can be unintended consequences for JavaScript-heavy websites. You can read all about how Google processes and indexes JavaScript here.

Rich Results

Search results that display additional information about a web page, such as reviews, ratings, or recipes. Rich results, such as a “featured answer” can help your website to stand out in search results and to attract more clicks.

Robots.txt

This is a website file that tells search engine crawlers/bots which pages on the website they should crawl and which they should not crawl. You can use a robots.txt file to prevent search engines from crawling pages that you don't want to be included in search results, such as login pages or private pages.

Schema

Schema is a type of code that you can add to your website to provide search engines with standardized information about your content. Schema markup according to schema.org conventions can help search engines to understand the meaning of your content and to display it as a rich result in the SERP. See also: Structured Data and Rich Results

SERP

Stands for "search engine results page". A SERP is the page a search engine displays after a user submits a query, made up of organic results plus features like rich results, ads, and knowledge panels. See also: Rich Results

Server-Side Rendering (SSR) / Client-Side Rendering (CSR)

Server-side rendering is when a web server builds a page's full HTML before sending it to the browser; client-side rendering is when the browser itself builds the page using JavaScript after receiving a mostly empty HTML shell. CSR sites are more reliant on search engines successfully rendering JavaScript to see the full content. Learn more in Sitebulb's Rendered Hints section. See also: Rendering (client side and browser side), JavaScript

Sitemap Index

A sitemap index is a "sitemap of sitemaps" — an XML file that lists multiple individual XML sitemaps, used on larger websites where the URL count exceeds the limit for a single sitemap file. Learn more in Sitebulb's XML sitemaps section. See also: XML Sitemap

Structured Data

A standardized format for providing search engines with information about your content. Schema markup is one type of structured data. Learn how to run a structured data audit here. Find out about Sitebulb’s structured data testing tool.

Thin Content

Thin content refers to pages that offer little to no unique value — very short pages, auto-generated text, or pages that largely duplicate other content on the site. Search engines may choose not to index thin content pages. See also: Duplicate Content

Time to First Byte (TTFB)

TTFB measures how long it takes a browser to receive the first byte of data from a server after making a request. It's an early indicator of server responsiveness and directly affects page speed and Core Web Vitals. Learn more in Sitebulb's Performance Hints section. See also: Page Speed/Page Load, Core Web Vitals

Title Tag

The title tag is an HTML element that specifies a web page's title, displayed as the clickable headline in search results and browser tabs. It's one of the strongest on-page ranking signals. Check out Sitebulb's on-page SEO analysis functionality here. See also: Metadata

XML Sitemap

An XML sitemap allows you to unambiguously declare exactly which URLs you wish to be indexed on a website. In essence, an XML sitemap file is a list of only the URLs you actually want indexed. You can find out more in Sitebulb’s XML sitemaps section or conduct a sitemap audit using Sitebulb.

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