What do the words in web addresses mean?

You can tell a lot about the website you're going to by examining the web address (or URL).

The first part of every web address – http:// – identifies the address to the computer as a web address. But what we're interested in here is primarily the next portion, the bit that's made up of words separated by dots and begins after the //, usually starting with www, and ending with something like .com or .co.uk. This piece is known as a ’domain name’.

Anything after another forward slash (eg the ‘music’ bit of www.bbc.co.uk/music) is a path telling the remote computer which page you're looking for and where to find it.

Every device that's connected to the internet has what's known as an ’IP address’ – that is, a number of the form 11.22.33.44. But most people don't find it easy to remember strings of up to 12 numbers, and in the late 1980s the domain name system was invented to assign names to these numbers to make it easier for humans.

The domain name part of the address reads from right to left in order of increasing specificity. So the .uk and .com are what's known as top-level domains and cover large sections of the net (there is a single registry for each of these).

The organisation name – for example, BBC – is the part you pay for when you register a domain. Top-level domains like .com, .net, and .org are called ’generic’ because they are not tied to a specific meaning like a country. Top-level domains that have two letters identifying a country, like .uk (Britain) or .de (Germany), are known as country code top-level domains.

• .uk – the country code domain for Britain. Within it, .co.uk means a company, .org.uk means a non-commercial organisation, .ac.uk means an educational establishment (such as a university) and .gov.uk means a government agency or department. Parliament is one of a handful of unusual sites that doesn't have an identifier like that – it's just parliament.uk.
• .com – originally intended for multinational commercial companies, .com is the most commonly used top-level domain. Almost all American and multinational organisations are registered in .com, as are many UK organisations.
• .org – originally intended for multinational non-commercial organisations, .org is frequently used by British organisations as well. In general, it's safe to assume that anyone registered in .org is non-commercial.
• .net – originally intended for internet service providers, .net is now a more or less general-purpose generic top-level domain and used as an alternative when .com is not available.

One more type of web address you're likely to come across are the very short ones commonly shared on social networking sites like Twitter and Facebook. Usually, these are made up of the domain name – such as bit.ly, tinyurl.com or is.gd – plus a few cryptic letters and numbers.

Many URLs are too long and complicated to fit into short messages or type accurately, and the companies that own these domains offer the service of shortening them. Because the site must translate them back into the originals when someone clicks on these links, the shortened URLs will only work as long as the companies stay in business.