Are there any restrictions or rules on the domain name I can choose to register?

The restrictions imposed on domains vary depending on what extension you are registering and what country the domain is associated with.

Domains can be formed using only use letters and numbers from the ASCII set of characters e.g. (a-z) (A-Z) (0-9). Hyphens are also allowed but must be surrounded by characters, therefore not at the beginning or end of the domain. You’re not allowed to use special characters (like ‘#*%’) and spaces cannot be used. 

General Rules

• Your domain must be unique, i.e. a domain name that is not already in use. 
• .com .net .org and .info domain names cannot exceed 67 characters.
• .info and .biz must have at least 3 characters not including .info and .biz
• Other domain names cannot exceed 22 characters not including the extension. 
• Domain names are not case sensitive.
• 2 letter domains are not allowed.

Common Extensions

• .com – used for commercial or personal sites
• .net – recommended for companies involved in internet infrastructure
• .org – recommended for not-for-profit organisations
• .info – used for commercial or personal sites
• .biz – restricted to commercial and business purposes
• .mobi – implies the website is designed for mobile usage

Common Country-Specific Extensions

• .ca – websites with a Canadian presence as defined by CIRA (Canadian Internet Registration Authority).
• .cc – Cocos (Keeling) Islands, to be used for commercial or personal sites
• .co.uk – United Kingdom for commerical or personal sites
• .de – Germany, to be used for commerical or personal sites
• .eu – websites with a presence in the European Union
• .org.uk – United Kingdom for charities and not-for-profit organisations
• .jp – Japan, to be used for commercial or personal sites
• .us – United States, to be used for commercial or personal sites