Hoth is a barren ice planet just on the outskirts of the the Mid-Rim of the Star Wars galaxy. The base is located on the sixth planet of the system. The planet is located near to Bespin. It is the location that The Rebel Alliance retreat to after dealing a devastating blow to the Galactica Empire at the end of Star Wars IV - A New Hope. It saw the Imperial forces land and attack with AT-AT Walkers, huge compat vehicles that walked on four legs. When the Imperial forces landed, the Rebel Alliance attempted to force their way through the planet blockade with two X-Wing Fighers giving each transporter protection.
The planet is continuously being hit by asteroids which the Rebel Alliance are lucky not to be hit by any. Unlike Starkiller Base which is a hollowed out snow world, there is no sign of vegetation but there are native life in the form of Wampa and Tauntaun. It is assumed that those creatures are native to the planet and not been bought there by the Alliance.
When Han Solo is forced to destroy an Imperial Droid which got alerted to Chewbacca's presence, the Imperial fleet was ordered there by Darth Vader. The fleet came out of hyperspace too close to the planet by Admiral Ozzel which would then cost Ozzel his life by a Force strangulation by Darth Vader. It wasn't Ozzel who caused the Empire to be alerted but the destruction of the droid. The Rebel Alliance was already making escape plans from the planet when the Empire turned up.