Hormones are like messengers in your body that give orders to your cells to do particular things. They are chemicals that are manufactured by glands and released into the bloodstream, sort of holding a sign up with a type of cell's name on it (like a limo driver at the airport waiting to pick up a client.) Most cells ignore the hormone, but when it comes across the right one its chemical "message" is read and the cell starts to do what it has been told. This message could be a lot of different things, but generally it is meant to keep the body functioning and in balance. Too much of a certain hormone can have results such as your gym partner in 8th grade growing a mustache before everybody else or your girlfriend in the 9th grade freaking out on you during "that time of the month."