Fiber cement siding is an exterior building material used to cover the outside of buildings. It is made of sand, cement, and cellulose fibers formed into rigid panels. Fiber cement siding is durable, fire and impact resistant, and requires little maintenance. It is more expensive than vinyl siding but provides better insulation and durability than wood siding. Fiber cement siding comes in various styles and colors and can last over 50 years with proper installation and care.