In terms of getting MIDI in you can use your computer’s keyboard, a regular MIDI keyboard or a more specialised MIDI control surface. This lets you incorporate older, more traditional hardware that might be fiddly to program into the much more user-friendly world of FL Studio where putting together complex parts is much easier than it ever was using outboard kit. You can use MIDI tracks to trigger external hardware too of course, and route the audio signal from synths, drum machines and other MIDI hardware back into FL Studio for recording. In fact the only thing that uses resources is whatever yous end the MIDI to in order to make sound, typically a software instrument. It’s weightless too, meaning that MIDI data uses virtually no space and no CPU power. MIDI can be copied, pasted, altered, manipulated and re-routed easily. The great thing about basing a lot of your composition on MIDI tracks is that they are almost endlessy flexible, with none of the limitations of digital audio files.