The fuselage as you know it’s the part of the aircraft which holds the passengers or cargo, or both at the same time. The weight of this part is very important, The centre of gravity of an aircraft must be carefully analysed and studied. The centre of gravity is the point of reference from which an aircraft rotates laterally or vertically.
The shape of the fuselage is determined by the type of the aircraft: a supersonic aircraft will not have the same fuselage shape as a commercial plane. The supersonic ones have a slender body to avoid the drag created by the fuselage on high speeds.
The fuselage (in commercial aircraft) is mainly divided in three different parts: the fuselage cockpit, the centre fuselage and rear fuselage.
In the cockpit is where the aircraft is controlled by the pilots. It is full of buttons, handlers and screens: they give the pilots information about what is happening in the moment on the aircraft. Most modern cockpits are enclosed after the September, 11 attacks, to avoid hijacking of the aircraft.
In the rear of the fuselage we usually find the vertical and horizontal stabilizer. The horizontal stabilizer is a fixed part of the aircraft that avoids it to rotate up and down. A part of the horizontal stabilizer can be moved and is called elevator and it’s the responsible of the position of the nose of the aircraft: pitching (up or down). It rotates along the centre of gravity as we said before. Here is a beautiful GIF that shows how it works: