Roof shingles are a roof covering consisting of individual overlapping elements. These elements are typically flat, rectangular shapes laid in courses from the bottom edge of the roof up, with each successive course overlapping the joints below. Shingles are made of various materials such as wood, slate, flagstone, fiber cement, metal, plastic, and composite material such as asphalt shingles. Roof shingles are a very common roofing material. Roof shingles are almost always highly visible and so are an important aspect of a building's aesthetics in patterns, textures and colors. The type of shingle is taken into account before construction because the material affects the roof pitch and construction method.