TLD

Acronym. Top-Level-Domain.

The "suffix" of a domain separated with a period (or dot):

• .com is the TLD of http://www.marketruler.com
• .co.uk is the TLD of http://www.google.co.uk
• .to is the TLD of http://pw.ex.to/

Some TLDs include two "words" (.co.uk) and some include one. The reasons are largely political.