In the past, people used windmills to grind corn and pump water. Today, modern windmills use the wind to generate electricity. They transform the energy in the wind into mechanical power, which can then be used to produce electricity. The UK is the windiest country in Europe and has relatively high average wind speeds. So it is an appropriate place to use the wind in this way.
Wind turbines can be very big.
Most are in places where the wind is strongest, such as Wales, Scotland and Cornwall. Look at the map to see where some of the main wind farms are - perhaps it would be possible for you to visit one. Already, UK wind farms make enough electricity for many thousands of homes. Wind turbines used in wind farms are usually about 60 metres tall. Other wind turbines are very small.