Extension and telescoping ladders have separate sections that slide apart to extend their length and lock into place for security. They adjust to different lengths and structures and are commonly used to access various height levels in applications like construction, maintenance, and utility work. Extension ladders expand their height to provide reach to high areas. Telescoping extension ladders extend and adjust to different heights and collapse into a compact size for transport and storage. Trestle extension ladders are stepladders with extra center sections that extend upward for greater reach and act as a trestle to hold scaffolding planks.