Flashings are used for water proofing. Usually installed in transition areas, flashings are used to direct water away from a particular area, and towards another.
Gutter flashings (a.k.a. gutter apron) are installed underneath the the roofing and into the gutter.
Gutter apron keeps the water from running behind the gutter. Flashings are 2" x 3" x 10 ft. long and are bent at a 35 degree angle.
Counter Flashings are installed at junctures in the roof such as the chimney or where a roof and a wall meet. They keep any rain water from running underneath the roofing materials.
Baby Tins are installed in roof transitions where the pitched part of the roof meets an adjacent wall. They are placed over each course of shingles and direct the water to go on top of the shingle that runs below it.