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The A-Z of modern web terms (that isn’t impossible to understand)

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By Davs Howard

6 min read

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When it comes to web terminology, there’s a lot of jargon floating around.

Sure, we’re guilty of it too sometimes.

But that’s why we’ve put together this handy glossary of terms. Clear, concise and uncomplicated - just the way it should be.

A/B Testing

A/B testing is a way of comparing two versions of a webpage or app against each other. Why? Basically, just to see which one performs better. It’s also known as split testing or bucket testing.


API stands for Application Programming Interface. Essentially, this is what allows two computer applications to “talk to each other”.


Accessible Rich Internet Applications (ARIA) is a technical specification that’s designed to ensure web content and applications are accessible for people with disabilities.


A branch is a separate version of the same code base. It allows two programmers to work on separate versions of the same website without interfering with each other.


Caching is a technology that increases the speed of your website without sacrificing anything in the process. It does this by temporarily storing static assets, e.g. images. Consequently, it’s much faster to retrieve this information from the cache the next time it’s needed.


A content delivery network (CDN) is a group of servers that protects businesses from cyber attacks and speeds up the delivery of web content. This is because they’re geographically distributed, placing them closer to where users actually are. CDNs are optimised so that HTML, JS, CSS, images and videos can be transferred quickly. They also utilise caching, which further improves speed and reduces bandwidth.

Client-side / Server-side

The client-side of a website refers to the web browser, whilst the server-side is where the data and source code is stored. Client-side and server-side are also known as the front-end and back-end.


A content management system (CMS) lets you edit, manage, and maintain existing website pages. Importantly, you can do so without needing specialist technical knowledge.


Cookies are files created by websites you visit. They save browsing information in order to show you relevant content. To do so, the cookie file is stored locally in your browser's folder or subfolder. Your browser then accesses the cookie file again when you visit the website that created it. Essentially, it’s a way to track, collect, and store any data that companies request.


This is the process of taking updates from your test, local development or staging/UAT environment, before making them live.


DNS stands for Domain Name System. Essentially, this is how the internet converts alphabetic names into numeric IP addresses. So when you type a web address into the browser, the DNS will return the IP address associated with that name. Just think of a postal address and how it refers to a specific property.


The following terms are all ways to measure website performance and user experience.


First Contentful Paint (FCP) measures perceived load speed by marking the first point where a user can see anything on the screen. Ever just sat there for what felt like an eternity waiting for a web page to load? That site has a bad FCP. Basically, a speedier FCP reassures the user that something’s happening.


Largest Contentful Paint (LCP) measures when the biggest piece of content becomes visible. Examples of LCP elements include hero images, text paragraphs, image carousels or video thumbnails. As these are very often the first things that pop up, LCP is a good way of reassuring users that the page is actually useful. Poor LCP is often caused by slow server response times.


Time to Interactive (TTI) measures how long it takes for a web page to become fully active. One issue it can uncover is hidden offscreen images. Loading offscreen images can lead to the browser taking too much time to load content that users just don’t need initially. TTI can also help identify pages that look interactive but aren’t actually usable yet.


Total Blocking Time (TBT) measures the usability and responsiveness of a web page while it loads. A slow TBT can be caused by long tasks, e.g. unnecessary JavaScript loading. Essentially, the site might be doing work that’s not needed to load the page.


Cumulative Layout Shift (CLS) measures website instability. Does the site behave as users expect it to? CLS can help you find out. This metric identifies unexpected issues that might disrupt a page, e.g. ads loading and pushing content down.

Headless CMS

A headless CMS is a content management system that manages and organises content alone, without a connected “front end” (so what the user sees on the page). This is different to traditional CMS which deals with the content and the front end. Content within the headless CMS can be distributed anywhere you want, e.g. website, mobile, CRM, via an API (see above).


Hosting means housing, serving, and maintaining files for one or more websites.


This is usually used to refer to “responsive web design”. A responsive website automatically adjusts for different devices, e.g. mobile, tablet and PC. It allows users to browse the site from any of these devices and it will still function properly.


SEO stands for search engine optimisation. This is a set of practices that are designed to improve the appearance and positioning of web pages in organic search results.


A group of website user interactions that take place within a single time frame, e.g. a single session could include multiple page views, social interactions and eCommerce transactions.

Static / Dynamic

A static website allows every user to see the exact same thing on each individual page. On a dynamic website, the content will change per user.


WYSIWYG (pronounced "wiz-ee-wig") stands for "what you see is what you get". This type of editor or program allows developers to see what the end result will look like while the interface or document is being created.


Two-factor authentication (2FA) is a security process that asks users to provide two different authentication factors to verify themselves. It's also known as two-step verification or dual-factor authentication

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