A top-level domain (TLD) is the last part of an Internet domain name, which is the letters which follow the final dot of any domain name.
.aero - for the air transport industry
.biz - for business use
.cat - for Catalan language/culture
.com - for commercial organizations, but unrestricted
.coop - for cooperatives
.edu - for post-secondary educational establishments
.gov - for governments and their agencies in the United States
.info - for informational sites, but unrestricted
.int - for international organizations established by treaty
.jobs - for employment-related sites
.mil - for the US military
.mobi - for sites catering to mobile devices
.museum - for museums
.name - for families and individuals
.net - originally for network infrastructures, now unrestricted
.org - originally for organizations not clearly falling within the other gTLDs, now unrestricted
.pro - for certain professions
.travel - for travel agents, airlines, hoteliers, tourism bureaus, etc.
.asia - for the Asian community
.post - for postal services
.tel - for services involving connections between the telephone network and the Internet
.geo - for geographically related sites