The restrictions on domains vary depending on what extension you are registering and the country with which the domain is associated.
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, not at the domain's beginning or end. 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 used.
- .com, .net .org, and .info domain names cannot exceed 67 characters.
- .info and .biz must have at least three 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 organizations
- .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).
- .rw - Rwanda for commercial or personal websites
- .co.rw - Rwanda for corporate websites
- .org.rw - Rwanda for non-profit organizations
- .ac.rw - Rwanda for Academic institutions
- .cc - Cocos (Keeling) Islands, to be used for commercial or personal sites
- .co.uk - United Kingdom for commercial or personal sites
- .de - Germany, to be used for commercial or personal sites
- .eu - websites with a presence in the European Union
- .org.uk - United Kingdom for charities and not-for-profit organizations
- .jp - Japan, to be used for commercial or personal sites
- .us - United States, to be used for commercial or personal sites