1. Intro

You may have notice in diferent host terminoligy eg: .us .uk ..
That is caled TLD (Top Level Domain), and it is used to identify geograficly were is that user located, of course that can easly be changed, and can sometimes be used in order to hide the real user country.

2. List

Here you can found a brief list of TLD (this is shufled by leter name):

A
.ac Ascension Island
.ad Andorra
.ae United Arab Emirates
.af Afghanistan
.ag Antigua and Barbuda
.ai Anguilla
.al Albania
.am Armenia
.an Netherlands Antilles
.ao Angola
.aq Antarctica
.ar Argentina
.as American Samoa
.at Austria
.au Australia
.aw Aruba
.az Azerbaijan
.ax Aland Islands