Redstone

                                                                 REDSTONE

redstone is minecraft's cable it is used for wiring. There are two types of pistons there are sticky pistons and pistons. Pistons are used for all sorts of things like gates,doors,cannons,things to push,elevators and escalators ect. Sticky pistons are pretty much the the same but most things stick to them.

There is allot that you can do with them almost anything. I've found them very handy.
Redtone repeaters are simple they are use to refresh the redstone connection, or to power the block in front of it. But they don't power the block underneath.