Blocks and tackles are a type of pulley system used to hoist heavy objects. The term 'blocks and tackles' refers to the combination of pulleys and ropes that are used to lift or lower an object. The pulleys are referred to as blocks, while the ropes are referred to as tackles. The use of multiple pulleys and ropes allows for a mechanical advantage, allowing for heavier objects to be lifted with less effort. HOISTS are a type of block and tackle system that are used to lift and move heavy objects.