The language of the web, without the jargon.

A method of comparing two versions of a page or element by splitting traffic between them to see which performs better against a goal. It replaces guesswork about copy, layout or buttons with measured evidence.

The portion of a page visible without scrolling on first load. It carries the heaviest weight for first impressions, so the core message and primary action usually belong here.

The practice of designing and building sites so that people with disabilities can perceive, understand and operate them. Done well, it also improves usability for everyone, including keyboard and mobile users.

A short written description of an image, read aloud by screen readers and shown when an image fails to load. It is also used by search engines to understand visual content.

An Application Programming Interface is a defined contract that lets two systems exchange data and trigger actions. Modern sites use APIs to pull in content, payments, search and other services.

A link from another website pointing to yours. Search engines treat relevant, trustworthy backlinks as votes of confidence that can lift rankings.

The share of visitors who land on a page and leave without any further interaction. A high bounce rate can signal a mismatch between expectation and content, slow loading, or unclear next steps.

A screen width at which a responsive layout changes to suit the device, such as switching from a single column on phones to multiple columns on desktops.

Storing a ready-made copy of data or a page so it can be served again without redoing the work. Caching is one of the most effective ways to make a site feel fast.

A Content Delivery Network is a global set of servers that caches your files close to users. Serving assets from a nearby location cuts latency and speeds up page loads.

Cumulative Layout Shift measures how much visible content unexpectedly moves while a page loads. Low CLS means the layout stays stable, which avoids the frustration of mis-taps.

A Content Management System lets non-developers create and edit site content through an admin interface rather than touching code. It separates the people who write from the people who build.

A measure of the difference in luminance between text and its background. Meeting minimum contrast ratios keeps text readable for low-vision users and in bright conditions.

The percentage of visitors who complete a desired action, such as buying, signing up or booking a call. It is the clearest single signal of whether a page is doing its job.

A set of Google metrics for real-world page experience, covering loading, interactivity and visual stability. They feed into search ranking and are a practical health check for speed.

The number of pages a search engine is willing to crawl on your site within a given time. Large sites manage it so the most important pages get discovered and refreshed promptly.

A shared library of reusable components, tokens and rules that keeps an interface consistent and faster to build. It is the single source of truth for how a product looks and behaves.

A named value for a design decision, such as a colour, spacing step or font size, stored once and reused everywhere. Tokens let you change a theme in one place rather than hunting through code.

A third-party score estimating how likely a domain is to rank in search results, based largely on its backlink profile. It is a directional signal, not an official Google metric.

The small icon shown in browser tabs, bookmarks and history for a site. A clear favicon helps users find your tab among many and reinforces brand recognition.

The sequence of steps a visitor moves through toward a goal, from first visit to conversion. Mapping the funnel shows where people drop off so you can fix the weakest stage.

A content system that stores and serves content through an API without dictating how it is displayed. The front end is built separately, giving teams freedom over design and performance.

The prominent section at the top of a page, usually combining a headline, supporting text and a primary action. It sets the tone and tells visitors what they have found.

An HTML attribute that tells search engines which language and region a page targets. It helps the right version of a multilingual site appear for the right audience.

The process by which a search engine stores and organises pages so they can be returned in results. If a page is not indexed, it cannot rank for anything.

The structure and labelling of content so people can find what they need and understand where they are. Good information architecture is the backbone of intuitive navigation.

The delay between a request and the first byte of a response. Lower latency makes interactions feel instant; high latency makes even fast sites feel sluggish.

Largest Contentful Paint measures how long it takes for the biggest visible element to render. It is the key Core Web Vital for perceived loading speed.

An open-source auditing tool from Google that scores a page on performance, accessibility, best practices and SEO. It produces actionable reports for improving each area.

Information about a page, such as its title and description, used by browsers, search engines and social platforms. Well-written metadata shapes how a page appears in results and shares.

A set of metadata tags that control how a link looks when shared on social platforms, including its title, description and preview image. It makes shared links look intentional rather than broken.

A strategy of building a working baseline experience first, then layering on richer features for capable browsers. It keeps a site usable even when scripts fail or the device is limited.

An approach where a single layout adapts fluidly to any screen size rather than shipping separate sites. It is the default expectation for modern web projects.

A file at the root of a site that tells crawlers which areas they may or may not access. It guides crawl behaviour but does not by itself keep a page out of search results.

Structured data added to a page so search engines can understand its meaning, like a product, review or event. It can unlock rich results such as star ratings and prices in listings.

Using HTML elements according to their meaning, such as headings, lists and buttons, rather than generic containers. It gives assistive technology and search engines reliable structure to work with.

A file listing the important pages of a site to help search engines discover and prioritise them. It is especially valuable for large or newly launched sites.

Server-Side Rendering builds a page on each request, while Static Site Generation builds pages ahead of time. Both deliver ready-made HTML for faster first loads and better SEO than client-only rendering.

Watching real people attempt tasks on a product to find where they struggle. A handful of sessions often surfaces the biggest problems before launch.

Tags appended to a URL that record where a visit came from, such as a campaign or channel. They let analytics attribute traffic and conversions to specific marketing efforts.

The visible area of a web page on a given device. Setting the viewport correctly is what lets a responsive site scale properly on phones instead of zooming out a desktop layout.

The Web Content Accessibility Guidelines are the international standard for making web content accessible, organised into levels A, AA and AAA. Most projects aim for AA as a practical baseline.

A low-fidelity sketch of a page that shows structure and priority without colour or styling. Wireframes let teams agree on layout and content before investing in visual design.