Butt Joint: This is when two pieces of woods are joined by simply butting them together and it is the simplest joint.
Miter: Mitered butt joints are very simple but a little more complex because an angle is involved. Usually, you will have two pieces cut at 45 degrees to create a square corner, but they could be cut at any angel to create any shape. This is a very common joint for frames, boxes, case work, and a ton of applications.
Dados, Grooves and Rabbets: These joints are very simple but they form a basis for a lot of other joints.
Tongue and Groove: Groove is carved out of a channel cut along the grain of the wood while the mating piece, the tongue, is cut by making two rabbets on either face of the wood.
Lap joints: This is where an area is cut away from both pieces of wood so they look into each other and become flush.
Bridle Joint: This is similar to lap joint in that the pieces interlock with each other except instead of having the material it gets divided.