Minecraft Wiki

Redstone mechanics provide Minecraft with a loose analogue to electricity, which is useful for controlling and activating a variety of mechanisms. Redstone circuits and devices have many uses including automatic farms, controlling doorways, changeable or mobile buildings, transporting players and mobs, and more.

Redstone construction can range from fairly simple to deeply complex. While there is not a single overarching tutorial, there are many relevant pages under both the "Mechanics" and "Tutorials" trees. Some relevant pages include:

Some pages dealing with specific blocks:

Circuits can be built into more complex devices:

Perhaps the most ambitious redstone project of all is to build a working computer within Minecraft!

Most of the farming tutorials also include complete devices, including Tutorials/Egg farming and Tutorials/Cobblestone farming. Many traps also use redstone.