A more thorough explanation:

The Duchy of Lancaster is a piece of land located in the county of Lancaster, as well as around the Savoy in London and Westminster. It was originally owned by the Duke of Lancaster, but later became property of the Crown in right of the Duchy.

For example, the Duchy of Lancaster includes various properties such as farms, commercial buildings, and residential properties. These properties generate income for the Crown, which is used to support the British monarchy.

The Duchy of Lancaster is an important part of British history and continues to play a significant role in the country's economy today.