A wind energy conversion
system (WECS) that is used, among other purposes, to grind grain, and
that typically has a high-solidity rotor; the term "windmill" is often used
to refer to all types of WECS. Windmills have been used by humans since
at least 200 BC for grinding grain and pumping water.
The idea spread to Europe in the Middle Ages. Their use was widespread during
the early years of the Industrial Revolution, but declined with the development
of the steam engine in the 19th century.
| Berkswell Windmill, West Midlands,
By the 1900s, windmills were used on farms and ranches in the United States
to pump water and, later, to produce electricity. Traditional windmills
have more blades than modern wind turbines,
and they rely on drag to rotate the blades.