.com = Commercial
Is the most widely used extension in the world and represents commercial sites, which can be biased but can also provide useful information.
.net = Network
Was originally intended for sites related to the Internet, but now used for a variety of sites.
.org = Organization
Originally intended for non-commercial "organizations", but now used for a wide variety of sites.
.edu = Educational
Used for educational institutions like universities and colleges, these sites usually provide factual information.
.biz = Business
Used for small business sites.
.gov = Government
Used for U.S. Government sites, these usual present factual information.
.mil = Military
Used for U.S. Military sites.
.int = Intergovernmental
Used for registering organizations established by international treaties between or among national governments.
The Domain Name System acts like a phone book for the Internet by translating IP addresses into user-friendly computer hostnames, or domain names, which are the suffixes found at the end of website URLs.