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Web words glossary

DictionaryThe web is packed with jargon. Use this guide to understand some of the essentials.

40x Error - an error message sent out by a web server when there is a problem dealing with a request. For example, a 404 error means the file that has been asked for can't be found. If the file exists, but you're not allowed to download it, you get a 403 error.

Accessibility - Designing websites so that they can be used by people with disabilities. For example, blind people might use a screen reader, which reads text aloud. Web pages should be designed to work well with screen readers - for example, by including descriptions with important images.

Ajax - A way of combining various web technologies, such as JavaScript and XML, to make web pages that can load new information without reloading the whole page. Examples include Google Maps.

Client - the software or computer that is accessing a website or service.

CMS (Content Management System) - software used to publish content and maintain a website.

Cookie - a small file stored on your computer by your web browser, which stores information about your visit to a website for next time you use it.

Crawler/spider - a program that automatically scans web pages - for example, to put in a search engine's database.

CSS (Cascading Style Sheets) - A language which sets rules for how an HTML page should be presented, including things like layout and font. This can be a separate file from the HTML, allowing the same CSS to be used across different pages, or it can be included as part of the HTML document.

DNS (domain name system) - the system that translates readable addresses like '' into an IP address.

Domain - the 'main' part of a web address, such as the 'bbc' in ''.

FTP (file transfer protocol) - a set of rules for sending files from one computer to another, such as when uploading files to a website.

HTML (hypertext markup language) - the language used to 'mark up' web pages to indicate which parts are links, headings and so on.

IP address - a set of numbers that identifies a computer connected to the internet, like a phone number identifies a phone.

JavaScript - a programming language that can be used in web pages to create interactive websites.

HTTP (hypertext transfer protocol) - the set of rules used to send text, such as web pages, over the internet.

robots.txt - a file on a website that sets rules for which parts of the site automated programs are allowed to look at.

RSS feed - a system for sharing content, like a blog or a podcast, in a way that can be processed by a computer. People can subscribe to the feed and see any updates in an RSS reader (e.g Google Reader). RSS can also be used for automated tasks like posting to Twitter whenever you update your blog.

SEO (Search Engine Optimization) - Making a website appear higher up and more often on search engines - for example, by making sure the headings are appropriate for the content.

Server - the computer that a web page or file is stored on, and which sends it out to the browser.

SQL (Structured Query Language) - a programming language for working with databases. Lots of database programs used to store the content of websites use SQL.

SSL (Secure socket layer) - a way of encrypting information sent over the internet, so that it can't be intercepted. When SSL is used on a website, the URL starts with 'https://' instead of 'http://'.

TLD (top level domain) - the '.com', '.net' etc. part of a URL. They can be used to indicate where a website is based (eg. .uk or .fr), or what kind of site it is (eg. .gov or .edu).

TLS (transport layer security) - An improved version of SSL.

URL (Uniform resource locator) - the address used to point to a particular page or file on the internet.

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