Some ladders are made in one piece. They can be carried around and made to lean against something such as the wall of a house. There should be a good distance between the bottom of the ladder and the wall so that the ladder is not too vertical, otherwise the ladder might fall backwards and the climber would fall off. Sometimes these ladders are extension ladders. Extension ladders are made in two or more sections so that the ladder can fold up to make it easier to carry about and to store. To open up the ladder, each section slides up almost to the top of the next section.