SEO Glossary: 30 Essential Terms Defined

Algorithm

The set of rules Google uses to rank web pages. Google runs thousands of algorithm updates per year, most minor and unannounced.

Alt text

A text description of an image added via the alt attribute on an img tag. Used by screen readers for accessibility and by Google to understand image content.

Anchor text

The clickable, visible text of a hyperlink. Google uses anchor text as a relevance signal for the linked page.

Backlink

A link from another website pointing to your site. Backlinks from authoritative, relevant sites are among the strongest ranking signals.

Canonical tag

An HTML tag (link rel=canonical) that tells search engines which version of a page is the preferred, master version to index.

Crawl budget

The number of pages Googlebot will crawl on your site within a given time period. Large sites with many low-quality pages may not have all pages crawled.

CLS (Cumulative Layout Shift)

A Core Web Vital measuring how much page content shifts visually during loading. Google requires a score under 0.1 for a Good rating.

Core Web Vitals

Three Google ranking signals measuring user experience: LCP (loading), INP (interactivity), and CLS (visual stability).

Crawling

The process of Googlebot discovering and downloading web pages by following links and processing sitemaps.

Domain Authority

A third-party metric (Moz) predicting how likely a domain is to rank in search results. Not a Google metric - Google uses its own internal authority signals.

E-E-A-T

Experience, Expertise, Authoritativeness, and Trustworthiness. Google's quality framework for evaluating content quality, especially in YMYL (health, finance) topics.

Featured snippet

A highlighted answer box appearing at the top of Google search results, above the regular organic results. Also called position zero.

Hreflang

An HTML attribute telling Google which language and region a page is intended for, used for international sites with multiple language versions.

Indexing

The process of Google storing and organizing a crawled page so it can appear in search results.

INP (Interaction to Next Paint)

A Core Web Vital measuring how quickly a page responds to user interactions. Google requires under 200ms for a Good rating.

Internal link

A link from one page on a website to another page on the same website. Internal links pass PageRank and help Google discover content.

LCP (Largest Contentful Paint)

A Core Web Vital measuring how long the main content takes to load. Google requires under 2.5 seconds for a Good rating.

Long-tail keyword

A longer, more specific keyword phrase with lower search volume but usually higher conversion intent and lower competition.

Meta description

An HTML meta tag summarizing a page's content. Shown under the title in search results. Not a direct ranking factor but affects click-through rate.

Noindex

A meta tag or HTTP header directive telling search engines not to include a page in their index.

Organic traffic

Visitors who arrive at a website by clicking an unpaid search result, as opposed to paid ads.

PageRank

Google's original algorithm for measuring page authority based on the quantity and quality of inbound links. Now one of hundreds of ranking signals.

robots.txt

A text file at the root of a domain telling crawlers which pages they are allowed or not allowed to crawl.

Schema markup

Structured data code added to pages to help search engines understand content and generate rich results like star ratings and FAQs.

SERP

Search Engine Results Page - the page Google shows in response to a search query, containing organic results, ads, and various SERP features.

Sitemap

An XML file listing URLs on a website to help search engines discover and index pages efficiently.

Technical SEO

The process of optimizing a website's infrastructure - crawlability, indexing, speed, structured data - to improve search engine visibility.

Title tag

An HTML tag defining the title of a web page. Shown as the clickable headline in search results and is one of the most important on-page ranking signals.

XML sitemap

A machine-readable file in XML format listing the URLs of a website, submitted to Google to aid in crawling and indexing.

YMYL

Your Money or Your Life - Google's category for content about topics that could significantly impact a person's health, finances, safety, or wellbeing. These pages face stricter E-E-A-T requirements.