.to is the Internet country code top-level domain (ccTLD) of the island kingdom of Tonga.

The government of Tonga sells domains in its ccTLD to any interested party. Because to is a common English preposition, it became popular to craft memorable URLs called domain hacks that take advantage of this; URL shortening/redirection services (e.g. go.to) are a popular use. Other domain hacks which do not use the to as a preposition include Daniel J. Bernstein's website cr.yp.to, London web development company Potato p.ota.to, and uploading services like uloz.to (which means "save it" in Czech).