- Domain names allow alphabetic and numeric characters only. Accented characters and symbols are not allowed. The only non -alphanumeric character allowed is a dash or multiple dashes. For example, www.your-domain.com or www.your--domain.com.
- The most commonly known top level domains are: .com, .net and .org. In addition to these, there are domains for a select number of countries such as: .us, .au and .me. There are also domains for various other organization such as colleges, the military and government agencies: .edu, .mil and .gov. Lesser known top level domains include .info and .biz. (See Ref. 3)
- Second level domains refers to what is left of the dot. For example, the second level domain in www.eHow.com is eHow. Third level domains take this idea one more step. The third level of www.eHow.com is www. Third level domains can also be used as sub domains. For example, blog.yourdomain.com or email.yourdomain.com.
- Unconventional domains use the the top level domain to create a word or brand because many .com domains are taken. For example, www.yourdoma.in/. This unconventional domain uses the top level domain name for India.
- Premium domains are domains that use well known words or are particularly short; usually five letters or less. Premium domains also include ones that are prefaced by an "I" or "E" which indicates the brand is online. Some premium domains include: eHow.com, cars.com and tradeshows.com. Premium domains are most often .com, but can be on other top level domains like .net, .info and .biz. (See Ref. 6)
