After MTV's Laguna Beach: The Real Orange County became one of the network's highest-rated programs, producers wanted to continue the story of one of its more popular characters, Lauren Conrad, as she moved to Los Angeles. After the cameras turned off for the Laguna Beach cast, those same producers stayed on to follow Conrad as she left her home in Laguna and moved on to a new life in Los Angeles. The Hills follows the daily lives of Lauren and friends, documenting all of the drama that eventually ensues. Despite being billed and formatted as a reality series, scripting is used for production purposes.

Source: Wikipedia.org