MIDI

Use your computer as an instrument.

What is MIDI?.

 Basically MIDI are instructions that allow the computer interpret notes. These instructions use inputs, like a keyboard, an electronic drum kit, even a mouse.

How to use MIDI?

 First you need a software MIDI-compatible and VST-compatible (Digital audio workstation, DAW). 
 A few DAWs:

• Cubase
• Pro tools
• Ableton
• Flstudio
• Logic(Mac)
• Reason
• Reaper
• Qtractor(Linux)
• Nuendo
• Acid pro
• Sonar

 With these DAWs you can plug your MIDI instrument and play, if you don't have you just use your mouse even some DAWs convert your keyboard in a piano(Ableton for example).

 What I can do with MIDI?

 A lot, really A LOT.  If you find the right VSTs you can emulate instruments like pianos, drums, synths, voices, basses, etc.

 Important: remember you are EMULATING, the VSTs won't sound like a real instrument but if don't have a choice they sound great.

 Today  electronic music use MIDI (95%) and VSTs (synths and frequency modulators mostly).

 Personally I use MIDI to create drum patterns (EzDrummer). Really simple but powerful tool.

 So if need a drum, a piano or maybe a synth, a MIDI(with VST) is a always a great option.