Why is your fan belt squealing?

The accessories on the engine cause alot of torque to be placed on the belt. When you first start the car the device whos belt is loose wont be up to speed and the belt spins causing it to squeal. Same thing if you are at a stop sign and step on the gas to go. The engine speeds up but the devise has to catch up. This is usually a quick fix and one person can do it. Some cars have a belt tensioner built in and it only takes a few turns to fix it. Others require a little longer but I havnt found a hard one yet.