Flashing is a part of repairing and putting on a new roof. Flashing is put on in strips to areas where different materials join together. An example is the juncture of a masonry chimney and the shingles or wherever the siding comes up to the roof line. Flashing will keep your home watertight if used were leakage is like to occur.
Image provided by Building Products of Canada Corp.
Shingles are the roof covering that consists of individual overlapping pieces. These pieces are usually flat rectangular shapes that are laid out in rows from the bottom edge of the roof to the peak. Each row overlaps the joins below. The roof point may have a cap comprising of copper or lead sheeting, but more than likely you will have a layer of shingles with a plastic layer underneath. Shingles are made from wood, asbestos-cement, ceramic or composite as well as slate and stone.