Midi keyboard
With a midi keyboard it is possible to play notes with a piano keyboard. Such a midi keyboard can also be useful for transcribing/arranging music.
Under MIDI settings you can choose which midi connection should be used as input for MIDI keyboard (some sound cards support more than 1 keyboard/MIDI port).
The MIDI keyboard must of course be connected to the computer. The usual way is a USB midi adapter.
Instead of a MIDI keyboard, you can also use the keyboard keys as a piano keyboard.
While editing on the notation bar, note input via MIDI can be toggled on and off with the 
button