A "block and tackle" is a simple mechanical system used to lift heavy objects. It consists of a combination of pulleys (the blocks) and a rope or cable (the tackle). By using multiple pulleys, the system reduces the amount of force needed to lift an object, making it easier to move heavy loads. This system is commonly used in various applications, such as in construction, sailing, and theater rigging. The arrangement of the pulleys can be adjusted to provide different mechanical advantages, allowing users to lift objects more efficiently and safely.