You have some electrons over here, and you want them over there but you don't want the electrons from over there to be able to come over here? That's what a diode is for, these are directional current valves and have the benefit of being waaay smaller than vacuum tubes.
Classic 1N4148's are great for any kind of small signal (not power!) rectification. Use them all the time, and they're very popular with folks making keyboards, so they come in a pack of 100.
Please note this is a surface mount part! It is possible to solder thin wires to the pads, but it's designed for use on an SMD PCB. If you are not comfortable with hand soldering SMD parts, check out our other through-hole ICs and transistors.
Want the through-hole style? We have a 10 Pack of 1N4148 here.