The ultimate SEO glossary : 50 terms you need to know!

A search engine algorithm is a set of mathematical rules and instructions used to rank web pages according to a query.

In SEO, it's fundamental to understand the criteria taken into account by the algorithm at each stage of its operation: crawling, indexing and ranking, in order to optimize the ranking of your site and pages on relevant searches.

The ALT attribute is used in HTML <img> tags as alternative text to describe an image when it cannot be displayed. It helps search engines understand the image content and improves accessibility for screen readers.

Using relevant keywords naturally in ALT tags contributes to image SEO and can drive additional traffic from Google Images.

In SEO, analytics refers to the collection and analysis of data to measure the performance of your website and SEO strategies.

Key metrics include organic traffic, bounce rate, conversion rate, keyword rankings, and user behavior. Popular tools are Google Analytics 4 and Google Search Console.

Authority score is a metric (used by tools like Moz, Ahrefs, SEMrush) that predicts how well a domain or webpage will rank in search engines based on its backlink profile, quality, and trustworthiness.

Higher authority generally makes it easier to rank for competitive keywords.

Backlinks (also called inbound links) are links from other websites pointing to your site. They are one of the strongest ranking signals because they act as "votes of confidence" from other sites.

Quality matters far more than quantity. Backlinks from high-authority, relevant sites carry the most value.

Black hat SEO refers to manipulative, unethical techniques that violate search engine guidelines (e.g., keyword stuffing, cloaking, hidden text) to gain quick rankings. These often lead to penalties or bans.

White hat SEO uses ethical, user-focused strategies that comply with Google’s guidelines and deliver sustainable long-term results.

Breadcrumb navigation shows users their current location within the site hierarchy (e.g., Home > Category > Subcategory > Product).

It improves user experience, reduces bounce rate, and helps search engines better understand site structure. Google often displays breadcrumbs in search results.

A canonical tag (<link rel="canonical">) tells search engines which version of a page is the preferred (master) one when duplicate or similar content exists.

It helps prevent duplicate content issues and consolidates ranking signals to the correct URL.

A core update is a broad algorithm change by Google that improves the overall quality of search results. These updates usually affect many sites and focus on content quality, relevance, and user experience rather than spam-fighting.

Core Web Vitals are a set of real-user metrics that measure loading performance, interactivity, and visual stability: Largest Contentful Paint (LCP), First Input Delay (FID/INP), and Cumulative Layout Shift (CLS).

They are an official Google ranking factor under Page Experience.

A crawler (also called spider or bot) is a program used by search engines to discover and scan web pages. Google’s crawler is called Googlebot.

Crawlers follow links, read page content, and send data back to the search engine for indexing.

Cascading Style Sheets (CSS) is the language used to control the visual presentation of a webpage (layout, colors, fonts, spacing).

Clean, optimized CSS improves page speed and mobile responsiveness, both of which are important for SEO.

In SEO, dereferencing usually refers to the process of resolving shortened or redirected URLs to their final destination. It is important for tracking accurate backlinks and ensuring proper link equity flow.

Keyword density is the percentage of times a keyword appears on a page compared to the total number of words. While once important, modern SEO focuses more on natural usage and topical relevance rather than strict density percentages.

Do-follow links pass link equity (ranking power) to the target page. No-follow links (rel="nofollow") tell search engines not to pass ranking signals or to crawl the linked page.

Since 2019, Google treats nofollow as a hint rather than a directive.

Domain Authority (DA) is Moz’s proprietary metric (0–100) that predicts a website’s ability to rank in search engines. It is based primarily on the quality and quantity of backlinks.

E-E-A-T stands for Experience, Expertise, Authoritativeness, and Trustworthiness. It is a key part of Google’s quality rater guidelines, especially important for YMYL (Your Money or Your Life) topics.

Demonstrating E-E-A-T through author bios, citations, and accurate content helps improve rankings.

A featured snippet is a special search result box that appears at the top of Google’s organic results, providing a direct answer extracted from a webpage.

Ranking in position 0 (featured snippet) can significantly increase visibility and traffic.

Google Search Console (GSC) is a free tool that helps website owners monitor and maintain their site’s presence in Google Search results. It provides data on indexing, performance, keywords, mobile usability, and issues.

Hreflang tags tell search engines which language and geographic version of a page should be shown to users in different regions (e.g., English for UK vs. US).

They help avoid duplicate content issues in international SEO.

Indexing is the process where search engines store and organize the content of web pages in their database after crawling. Only indexed pages can appear in search results.

Internal linking refers to hyperlinks that connect one page of your website to another. It helps distribute page authority, improves crawlability, and guides users to relevant content.

A keyword is a word or phrase that users type into search engines. Targeting the right keywords is the foundation of SEO content strategy.

Keyword research is the process of discovering, analyzing, and selecting search terms that people use to find information, products, or services. It involves evaluating search volume, competition, and intent.

Long-tail keywords are longer, more specific phrases (usually 3+ words) that have lower search volume but higher conversion rates and less competition (e.g., “best wireless noise cancelling headphones under 5000” instead of “headphones”).

The meta description is an HTML attribute that provides a short summary of a webpage’s content. While it doesn’t directly affect rankings, a compelling meta description can improve click-through rates from search results.

The meta title (title tag) is the clickable headline that appears in search engine results pages (SERPs). It is one of the most important on-page SEO elements and should include primary keywords while staying under 60 characters.

Mobile-First Indexing means Google primarily uses the mobile version of your website for indexing and ranking. Having a responsive, fast-loading mobile site is now essential for good SEO performance.

The noindex directive (via meta tag or HTTP header) tells search engines not to include a page in their search results index. It is useful for thin content, admin pages, or duplicate pages.

Organic traffic refers to visitors who arrive at your website from unpaid (natural) search engine results. It is the primary goal of most SEO efforts.

Page speed is the time it takes for a webpage to load completely. Faster pages improve user experience and are favored by Google’s ranking algorithms. Tools like PageSpeed Insights help measure and optimize it.

A Private Blog Network is a network of websites created specifically to build backlinks to a target site. PBNs are considered black-hat SEO and can result in severe Google penalties if detected.

A 301 redirect is a permanent redirect that passes nearly all link equity to the new URL. A 302 is a temporary redirect. Proper use of redirects is crucial during site migrations or URL changes.

Robots.txt is a file placed in the root directory of a website that instructs search engine crawlers which pages or sections they can or cannot access.

Schema markup (structured data) is code added to HTML that helps search engines understand the content and context of a page. It can enable rich snippets (stars, prices, FAQs, etc.) in search results.

Search intent is the reason behind a user’s search query — informational, navigational, transactional, or commercial investigation. Modern SEO focuses heavily on matching content to user intent.

An XML sitemap is a file that lists all important pages on a website to help search engines discover and crawl them more efficiently. It is especially useful for large or new websites.

SSL (Secure Sockets Layer) encrypts data between the user’s browser and the server. HTTPS is the secure version of HTTP. Google uses HTTPS as a ranking signal and shows “Not Secure” warnings on HTTP sites.

Structured data is a standardized format (usually JSON-LD) for providing additional information about a page’s content to search engines. It powers rich results and helps with better understanding of content.

Technical SEO involves optimizing the technical aspects of a website (site speed, mobile-friendliness, crawlability, indexability, structured data, security, etc.) so search engines can efficiently crawl, index, and rank the site.

The title tag is the HTML element that defines the title of a webpage. It appears as the blue clickable link in search results and is one of the most important on-page ranking factors.

Good URL structure is clean, descriptive, and includes target keywords when relevant (e.g., /best-seo-tips-2026 instead of /p=123). It improves user experience and helps search engines understand page content.

User Experience in SEO refers to how easy, fast, and pleasant it is for visitors to use your website. Google increasingly uses UX signals (Core Web Vitals, bounce rate, dwell time) as ranking factors.

Voice search optimization involves creating content that answers natural, conversational questions (usually long-tail) because people speak differently than they type (e.g., “What is the best Italian restaurant near me?”).

Zero-click searches are queries where users get their answer directly on the search results page (featured snippets, knowledge panels, “People Also Ask”) without clicking through to any website. SEO strategies now focus on appearing in these rich results.