A domain name is the unique label of a web document, based on the Domain Name System (DNS). The domain name of a web page usually gives an indication of the content residing there.

A domain name is made up of two parts,

internet-guide.co.uk

Part 1 is the second-level domain,

• internet-guide

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Part 2 is the top-level domain,

• co.uk

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Part 2 is an extension of a domain name, and can be split into further categories such as,

ccTLD - country code Top Level Domain

• .co.uk - United Kingdom

gTLD - generic Top Level Domain

• .com - commercial
• .co.uk - United Kingdom based address
• .org - non-profit organisation
• .gov - us government
• .int - international
• .mil - military
• .info - information
• .biz - only business
• .museum - museums

New extensions to domain names are being created all the time (such as uk.com). If you are interested in buying a domain name then you can check if it is available at whois.