The W3C CSS Validation Service is a free servicee offered by the W3C to help Web designers and Web developers check Cascading Style Sheets (CSS). What this tool does is help people authoring CSS check, and fix if necessary, their CSS Style Sheets.

A demonstration of what can be accomplished visually through CSS-based design

PHP.net is the official site for the PHP language. This site is an essential resource for all PHP developers, with a full list of functions and detailed explanations.

This tutorial is a great place to start if you are new to JavaScript. It covers all the essentials, with examples and a quiz to test your knowledge

Online Editor for the Web (JavaScript, MooTools, jQuery, Prototype, YUI, Glow and Dojo, HTML, CSS)

The Markup Validator is a free service by W3C that helps check the validity of Web documents. Most Web documents are written using markup languages, such as HTML or XHTML. These languages are defined by technical specifications, which usually include a machine-readable formal grammar (and vocabulary). The act of checking a document against these constraints is called validation, and this is what the Markup Validator does.

The official home of the world's most popular open-source database. A visit to the documentation library is essential for any developer wishing to optimise their MySQL database knowledge.

Customise and download your own background tiles using a clean & simple user interface. Choose your image, change the colour and even rotate to create a unique tile for use on your site

Experts-Exchange.com is an IT and computer solutions community of more than 50,000 experts dedicated to exchanging knowledge and solving your technical problems. Experts Exchange is the most efficient and reliable IT resource on the Internet as evident by more than 2.6 million tech solutions.

Simply the best browser on the Internet. Mozilla Firefox is a fast, secure (well more than IE) and fully customisable way to browse the web.

A webcomic of romance, sarcasm, math, and language.

Instructables is the Biggest How To and DIY community where people make and share inspiring, entertaining, and useful projects, recipes, and hacks

Tables charting the chemical elements have been around since the 19th century - but this modern version has a short video about each one.

A regularly updated blog containing a collection of random posts related to Chemistry

New Scientist online was launched in 1996 and now carries an archive of over 76,000 content pieces. The website includes news and features, engaging headlines, fascinating stories and amazing facts, delivered through the latest news slots, in-depth articles, video, blogs and commenting.

Dive Into HTML5 seeks to elaborate on a hand-picked Selection of features from the HTML5 specification and other fine Standards

This is a quick reference of elements that are new or have been redefined in HTML5. For each element there is a short description, a link to the specification, and a code example

HTML5 gallery has two primary aims, the first is to showcase sites that use HTML5 for markup, so that we can see how people have interpreted the specification and how they’ve implemented it. The second aim is to help people learn about html5, how it should be used and how to implement it

Archive of freely downloadable fonts. Browse by alphabetical listing, by style, by author or by popularity.

Google Web Fonts makes web fonts quick and easy to use for everyone, including professional designers and developers

The summits of the three thousand foot mountains of Wales can be visited in a single magnificent journey. It's around 24 miles from Yr Wyddfa (Snowdon) to Foel Fras and it's certainly not a mountain journey to be under-estimated. Succesful completions of the traverse may be entered in the Society's public database. In keeping with the ethics of mountaineering, we do not seek proof of claims. The system works on the personal honour of the person making the claim.

Try out the online mapping and route planning tool from the Ordnance Survey

A website for runners of every ability, from Runner's World, the UK's biggest running magazine. Packed with practical and informative pages, it includes discussion forums, training information, injury tips, shoe reviews and the UK's most comprehensive race diary

UK Weather forecasts and current conditions by AccuWeather.com including wind, temperature, and general conditions for England, Scotland, Wales, and Ireland