Houses (Skyrim)

Houses in Skyrim are buildings in which the player may sleep and safely store items in non-respawning containers. Each major city has a house, of varying size, quality and cost, available for the player to purchase. There is no limit to how many homes the player may own, only a limit on how many houses are available. If you get married, you may allow your spouse to live with you at [one of] your home(s).

Sleeping in a bed in your house provides a temporary boost to your Health and Magicka; the boost obtained by sleeping in your own bed is higher than that from other beds. However you will not gain any rested bonus if you have the Beast Blood effect from becoming a werewolf.

Here is an exemple of one of the houses. This is Hjerim in Windhelm. : http://www.youtube.com/watch?v=9gcAWyvzOkA

Achievements
Buying a house allows you to unlock one :
 * Citizen -- Buy a house
 * Note: Any of the free houses do not give you the Citizen achievement because they are not bought.