Flashing is a weatherproofing component made from thin, impervious materials such as metal or flexible membranes that prevent water from penetrating joints and openings in a building envelope. It is commonly installed around roofs, windows, doors, chimneys, and wall intersections to direct water away from vulnerable areas and reduce the risk of leaks, structural damage, and mold growth. Properly installed flashing is a critical element of a durable, code-compliant building enclosure that helps maintain long-term weather resistance (Wikipedia).