A system that finds, organizes, and ranks web pages in response to a user's query. Google is the dominant search engine globally, though Bing, Yahoo, and others operate similarly.

The page a search engine displays after a user runs a query. A SERP typically includes organic results, paid ads, and features like featured snippets or knowledge panels.

The unpaid, algorithmically generated listings on a SERP. Ranking well in organic results is the primary goal of most SEO work, as opposed to paid search results, which appear because an advertiser paid for placement.

The process by which search engines discover pages by following links across the web. A page can't be indexed or ranked if it's never crawled.

After a page is crawled, the search engine analyzes its content and stores it in an index — essentially a massive database it draws from to answer search queries. A crawled page isn't guaranteed to be indexed.

The number of pages a search engine will crawl on a given site within a given timeframe. This matters more for large sites with thousands of pages than for small business websites.

The set of rules and calculations a search engine uses to decide which pages rank for which queries. Google updates its algorithm regularly, sometimes with minor tweaks and occasionally with major "core updates."

A page's position in the SERP for a specific search query. Rankings can vary by location, device, and even the individual user's search history.

The signals search engines evaluate to determine how well a page satisfies a query — things like content relevance, site speed, backlinks, and mobile usability. There are hundreds of ranking factors, and no single one guarantees a top position.

Third-party metrics (not created by Google) that estimate how likely a website is to rank based on its backlink profile and overall strength. Useful for comparative research, but not an official Google metric.

A highlighted result at the top of a SERP that directly answers a user's query, pulled from a page's content. Landing a featured snippet often increases visibility even above the first organic position.

An information box, usually appearing on the right side of desktop search results, summarizing facts about a person, place, organization, or topic — sourced from structured data and trusted databases.

A SERP feature showing a list of related questions that expand to reveal short answers when clicked. PAA boxes reveal what else users want to know about a topic.

Optimization work done directly on a webpage — including content, HTML structure, headings, and internal links — to help it rank and to help users understand it. See our full on-page SEO guide for the complete breakdown.

The HTML element that defines a page's title tag, shown as the clickable headline in search results and in the browser tab. It's one of the clearest relevance signals a page can send.

A short HTML snippet summarizing a page's content, often shown beneath the title tag in search results. It doesn't directly influence rankings but affects whether users click. Learn more about meta descriptions.

HTML tags used to structure content hierarchically. The H1 typically represents the main topic, while H2s and H3s break the page into logical sections — helping both readers and search engines understand structure.

A written description added to an image's HTML, used by screen readers and search engines since they can't "see" images directly. It also serves as a fallback if an image fails to load.

A link from one page to another page on the same website. Internal links help search engines discover pages and understand relationships between topics, and they help users navigate.

The clickable, visible text of a hyperlink. Descriptive anchor text (rather than generic phrases like "click here") gives both users and search engines context about the linked page.

A word or phrase a user types into a search engine. SEO work often starts by identifying which keywords are relevant to a business and have meaningful search demand.

The process of finding and evaluating keywords based on search volume, competition, and relevance to a business's content or offerings. See our keyword research guide.

The underlying reason behind a search query — whether the user wants information, is looking for a specific website, is comparing options, or is ready to make a purchase. Matching content to search intent is one of the most important factors in ranking well.

A longer, more specific keyword phrase, typically with lower search volume but higher intent clarity. "Running shoes" is a broad keyword; "best running shoes for flat feet" is long-tail.

The outdated practice of overloading content with a keyword in an unnatural way, attempting to manipulate rankings. Modern search engines penalize this rather than reward it.

The degree to which a website is seen as a comprehensive, trustworthy source on a given subject, typically built through a body of interlinked, high-quality content covering a topic thoroughly.

The practice of optimizing a website's infrastructure — speed, crawlability, mobile-friendliness, security, and structured data — so search engines can access and understand it effectively.

An HTML tag that tells search engines which version of a page (when duplicates or near-duplicates exist) should be treated as the primary one for indexing.

A file listing a website's important pages, submitted to help search engines discover and crawl content more efficiently.

A file placed at a website's root that gives search engine crawlers instructions about which pages or sections should not be crawled.

Code added to a page that explicitly labels its content for search engines — for example, marking a page as a recipe, product, or review — which can enable rich results like star ratings in the SERP.

A set of Google metrics measuring real-world user experience, including loading speed, interactivity, and visual stability. These are part of Google's page experience signals.

How well a page functions and displays on mobile devices. Since Google primarily uses mobile-first indexing, it evaluates the mobile version of a site as the main basis for ranking.

The secure version of the HTTP protocol, indicated by a padlock icon in the browser. Google has confirmed HTTPS as a lightweight ranking signal and a baseline trust expectation.

Optimization activity that happens outside a website itself, primarily focused on building authority and trust — most commonly through backlinks.

A link from one website to another. Backlinks act as a signal of trust and relevance, particularly when they come from reputable, topically related sites.

When discussing backlinks, anchor text refers to the clickable text used on the linking site — its relevance and variety matter for a natural-looking backlink profile.

As noted above, an estimate of a domain's overall strength, often used to evaluate potential backlink sources during outreach.

HTML attributes on links that indicate whether a search engine should pass ranking value through that link. Nofollow links tell search engines not to pass that value; dofollow (the default) does.

Visitors who arrive at a website through unpaid search results, as opposed to paid ads, social media, or direct visits. Read our full breakdown of organic traffic.

The percentage of people who click a result after seeing it in the SERP. CTR is influenced heavily by title tags, meta descriptions, and SERP features.

The percentage of visitors who leave a site after viewing only one page. While not a direct Google ranking factor, it can indicate whether content is meeting search intent.

The percentage of visitors who complete a desired action — a purchase, a form submission, a sign-up — relative to total visitors. SEO ultimately supports conversions, not just traffic volume.