Rabbet joints are used mostly when building casework in the cabinetry or furniture trades. Cabinet makers and furniture makers alike make regular use this joint for it's dual purpose of easy parts alignment while covering the end grain of the opposing piece.
Just like dado joints it can be cut very shallow when used for alignment or it can be cut deep to make room to fasten the joint together with screws or nails. Either way the end grain of the opposing board is covered.
Since only one side is cut it makes the joint very easy to make. It can be cut on a table saw, radial arm saw, hand cut with a saw or cut with a router and bit. For those woodworkers that only work with hand tools it can also be made with a sharp chisel. If you need to make a lot of joints it's very easy to set up a permanent jig to eliminate set-up time.