Machinery refers to machines in general, or to a complex system of connected machines working together. A factory's machinery might include conveyor belts, robotic arms, stamping presses, and packaging equipment, all coordinated to manufacture products. A farm's machinery includes tractors, combines, and irrigation systems that help grow and harvest crops far more efficiently than doing everything by hand.

Before the Industrial Revolution in the 1700s, most work was done by human muscle power or with simple tools. The development of complex machinery transformed civilization. Machines that once required dozens of workers could suddenly be operated by just a few people. Textile machinery revolutionized clothing production. Agricultural machinery meant farmers could feed many more people. Today, machinery builds our cars, constructs our buildings, and manufactures nearly everything we use.

The word can also describe any complicated system with many working parts. The machinery of government refers to all the departments, processes, and people that make laws happen. A novel might describe “the machinery of fate” bringing characters together, comparing destiny to an intricate mechanism with many moving parts. When something involves complicated processes behind the scenes, we sometimes call it machinery even when no actual machines are involved.