Before you can re-use any component you have salvaged you really need to know what the components are. Some components are easy to identify, but others can be somewhat more tricky to find out just what it is.
Components can be loosly grouped into three groups - through hole, surface mount, and off-board. Surface mount components are soldered directly on to the surface of the PCB (hence the name), and through hole components have leads which pass through holes drilled in the PCB and are soldered on the reverse side. Off-board components usually have wires connecting them to the circuit board, and include things like transformers, motors and such.