301 redirect
A permanent redirect: it sends visitors and search engines from an old web address to a new one and tells Google the move is permanent. Redirects are how a redesign keeps the search traffic old pages earned. Google explains them in its redirects guide.
404 error
The response a website gives when a page doesn't exist. A few are normal; a 404 on a page that used to get visits or links usually means a redirect is missing.
Accessibility
Building a site so people with disabilities can use it: readable contrast, keyboard navigation, text alternatives for images, captions. The common standard is WCAG 2.2.
AI Overviews and AI Mode
Google's AI-generated summaries at the top of some search results (AI Overviews) and its conversational search mode (AI Mode). Google says no special optimization is needed to appear in them; see our AI answers guide.
Alt text
A short written description of an image, read aloud by screen readers and used by search engines to understand the picture.
Analytics
Software that counts visits and what visitors do on a site, such as Cloudflare Web Analytics or Google Analytics. It tells you which pages bring calls and form requests.
Backlink
A link to your site from another website. Links from real, relevant sites (a supplier, a local association, local news) are one of the signals Google uses to gauge how well known a business is.
Bing Places
Microsoft's free business listing for Bing search and maps, the equivalent of a Google Business Profile.
Call to action (CTA)
The one thing a page asks the visitor to do next, such as "Call now" or "Request a quote".
Canonical URL
The one preferred address for a page when the same content can be reached at several addresses. A canonical tag tells search engines which version to index. See Google's canonicalization guide.
CLS (Cumulative Layout Shift)
A Core Web Vitals measure of how much a page jumps around while it loads, such as a button moving just as you tap it. Google's "good" threshold is 0.1 or less (web.dev).
Core Web Vitals
Google's three measures of real-world page experience: loading (LCP), responsiveness (INP) and visual stability (CLS). A page passes when 75% of real visits meet the "good" threshold for all three (web.dev, Web Vitals).
Crawler (bot)
A program that visits web pages automatically to read them, such as Googlebot for Google Search or OAI-SearchBot for ChatGPT search.
CrUX (Chrome UX Report)
Google's public dataset of real-user speed measurements from Chrome. It is the "field data" PageSpeed Insights shows when a site has enough visitors (Chrome for Developers).
DNS
The internet's address book: the settings that point your domain name to your website and your email. Whoever controls your DNS controls where your site and email go.
Domain name
Your web address, such as yourcompany.com. Register it in your own name, with an account you control.
E-E-A-T
Short for experience, expertise, authoritativeness and trust: the qualities Google's guidance says helpful content shows (Google, creating helpful content).
Field data and lab data
Field data is measured from real visitors' browsers; lab data comes from a single simulated test. PageSpeed Insights shows both. Core Web Vitals are assessed on field data.
Google Business Profile
Google's free listing that shows a business on Maps and in local search results, with hours, reviews and photos. See our setup guide.
Google Search Console
Google's free service that shows how a site performs in Google Search: which searches show it, clicks, indexing problems and Core Web Vitals.
HTTPS
The secure version of a web address, shown with a padlock in the browser. It encrypts what passes between the visitor and the site.
Indexing
When a search engine stores a page so it can appear in results. A page that isn't indexed can't be found in search, however good it is.
INP (Interaction to Next Paint)
A Core Web Vitals measure of how quickly a page responds when someone taps or clicks. Google's "good" threshold is 200 milliseconds or less (web.dev).
LCP (Largest Contentful Paint)
A Core Web Vitals measure of how long the main content of a page takes to appear. Google's "good" threshold is 2.5 seconds or less (web.dev).
Lighthouse
Google's free, open-source tool that scores a page from 0 to 100 for performance, accessibility, best practices and SEO. PageSpeed Insights runs it.
llms.txt
A proposed plain-text file at a site's root that summarizes the site for AI agents (llmstxt.org). Google says Google Search doesn't use it; some AI tools may.
Local pack (map pack)
The block of map results with three or so businesses that Google shows for local searches such as "roofer near me". It is driven mostly by Google Business Profiles.
MCP (Model Context Protocol)
An open standard that lets AI assistants connect to outside tools and data, such as a business's catalog, through a "connector" or "MCP server".
Meta description
A short summary of a page written into its code. Google sometimes shows it under the title in search results (Google, snippets).
Mobile-first
Designing a site for phones first and then for larger screens, because most local searches happen on phones.
NAP
Name, address and phone number. Keeping them identical on your website, Business Profile and directories helps search engines trust the details.
Noindex
An instruction in a page's code that tells search engines not to show the page in results (Google, block indexing).
PageSpeed Insights
Google's free tool that tests a page's speed and quality on mobile and desktop, with real-user data where available. Try it at pagespeed.web.dev.
Rich results
Search results with extra features, such as review stars or event dates, made possible by structured data. Google decides when to show them. Test pages with the Rich Results Test.
robots.txt
A text file at a site's root that tells crawlers which parts of the site they may visit (Google, robots.txt introduction). Blocking the wrong bot here can remove a site from search or AI answers.
Schema markup (structured data)
Code in a page that describes facts, such as your business name, hours and services, in the shared schema.org vocabulary, so search engines read them reliably (Google, intro to structured data).
SEO (search engine optimization)
The work of making a site easy for search engines to find, understand and show for the right searches. Google says no one can guarantee a top ranking (Google Search Central).
Service-area business
Google's term for a business that serves customers at their location, such as a plumber, and usually hides its address on its Business Profile.
Title tag
The page title written into a page's code. Google often uses it as the clickable headline in results (Google, title links).
XML sitemap
A file listing the pages you want search engines to find, with the date each last changed (Google, sitemaps overview).