The terms "mobile" and "manufactured" and "modular" are sometimes used interchangeably, but there are important differences. The U.S. Department of Housing and Urban Development (HUD) states that a factory-built home constructed before June 15, 1976, is a mobile home. If it was built after this date, then it is called a manufactured home. A manufactured home has its mobile home parts assembled in a factory. They are built to federal code. While both manufactured and modular homes are a type of mobile home, both vary slightly. A modular home is also built in a factory like a manufactured home, however it must meet local state building codes. Modular homes are also built on either a permanent chassis or a one that is temporary.