CDN (Content Delivery Network)
How CDNs deliver static and cached content from edge locations to improve speed and reliability.
Quick definitions for common SEO, performance, and web terms.
How CDNs deliver static and cached content from edge locations to improve speed and reliability.
A measure of how much unexpected layout shift occurs while a page loads.
A security header that controls which resources a page is allowed to load.
An attack that tricks an authenticated user into unknowingly submitting requests to another site.
rel=canonical is used to indicate the preferred version of a page to search engines.
An attack that overlays invisible iframes to trick users into clicking unintended targets.
Server-side encoding that reduces text-based file transfer sizes for faster page loads.
A set of performance metrics (Largest Contentful Paint, Interaction to Next Paint, Cumulative Layout Shift) that measure user experience.
The number of pages a search engine will crawl on your site within a given timeframe.
An email authentication method that uses digital signatures to verify message integrity.
A policy that tells receiving mail servers what to do when SPF or DKIM checks fail.
The Domain Name System maps human-readable domain names to IP addresses and other records.
Maps a hostname to an IPv4 address.
Maps a hostname to an IPv6 address.
Specifies which certificate authorities are allowed to issue SSL/TLS certificates for a domain.
Aliases one hostname to another hostname.
Specifies mail servers responsible for receiving email.
Specifies the authoritative nameservers for a domain.
Stores arbitrary text data for a domain, often for verification.
DNS Security Extensions provide a way to verify DNS data integrity and authenticity.
Google's quality framework: Experience, Expertise, Authoritativeness, Trustworthiness.
The time until the first text or image is painted on the screen.
A legacy responsiveness metric measuring delay before the browser handles user input.
A security policy that forces browsers to only access a site over HTTPS.
The second major version of HTTP, introducing multiplexing and header compression for faster connections.
The third major version of HTTP, built on QUIC for faster and more resilient connections.
How HTTPS encrypts web traffic using TLS to protect data in transit.
A responsiveness metric measuring how quickly a page responds to user input.
A word or phrase that people use to find content in search engines.
The time it takes for the largest above-the-fold element to render.
Performance data measured in a controlled environment.
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An HTML tag summarising a page content, shown as the snippet in search engine results.
Meta tags that control how pages appear when shared on social media.
Performance data collected from real users in production.
How HTTP redirects work and when to use 301 (permanent) vs 302 (temporary).
A DNS record that specifies which mail servers are authorised to send email for a domain.
An attack where malicious SQL code is inserted into queries via user input.
The cryptographic protocols that secure data transmitted over the internet.
Using Schema.org and JSON-LD to add machine-readable context to your pages.
A lab metric estimating how much the main thread is blocked during load.
The time it takes for the first byte of a server response to reach the browser.
A DNS record property indicating how long a resolver may cache that record.
What a URL is and its parts (protocol, domain, path, parameters).
A simple guide to WCAG and the four POUR principles.
A web security vulnerability where attackers inject malicious scripts into webpages.
How to use hreflang annotations to target content by language and region.
Site guidance files for LLMs and AI crawlers — how you want your content to be used.
A directive that prevents a page from appearing in search engine results.
Small text file that tells crawlers which parts of a site to crawl or avoid.
What a sitemap is and how it helps crawlers discover your important URLs.