These are the 5 categories of musical instruments as far as I know them.
Membranophones- use a vibrating membrane to make a noise (ex. a conga drum)
Idiophones- The actual instrument vibrates (ex. a xylophone or a bell)
Aerophones- Moving air creates the sound (ex. a flute)
Chordophones- Vibrating string makes sound (ex. a banjo)
Electrophones- electronic production of a sound, coming out of a speaker (ex. keyboard)