Deconstructing Domain Names
The type of website you are purchasing a domain name for should play a factor in your decision. There are many domain name extensions to choose from, and several may suit your purposes.
The most common is .com, and you should try and incorporate .com into your domain name purchases if anything similar to your desired domain name is available in .com.
Beyond that, any website that sells product online should definitely use .com as it is intended for commerce. An informational website of an offline organization should consider .net as the 'net' version of the entity. Any organization including education, not for profit, business etc. can benefit from a .org domain name.
For websites that include a target demographic of Canadians, .ca is an excellent addition. For websites that include a target demographic of Americans, .us or .us.com are an excellent choice.
Businesses can benefit by adding a .biz domain name. A website that is informational in nature may consider a .info domain name. Video rich websites are making the .tv domain name extension popular. The second most popular domain name extension is .cc, making .cc a great addition or even a replacement to .com if your desired .com domain name is taken. Mobile users will appreciate your .mobi website designed for their mobile device.