Here is a brief guide on ladder. For many tasks, the rigid ladder is the type often used. Rigid ladders are available in many varieties, from the fixed to the roof ladders. The fixed ladder is the most basic, and has no moving parts. Extension ladders are composed of two ladders where one nests in the other for easy storage. Joined by a hinge at the top, and often forming an inverted V, are step ladders. If you need space to place things like paint cans, you might need a platform ladder, which has a platform at the top. Ladders that have hooks to set them locked on the roof are called roof ladders. Aluminium is the choice material for many ladders, except those for electrical work.