How are canals and locks related

The locks of a canal are used to move the canal up over the hills where the land is not very flat.

Explanation:

Canals are man made water bodies which are used to release water in large amount. They are used for production and development purposes. But the area which are not very flat, locks are built there so that the level of water can be altered. Locks of a canal are built to allow the canal to move up and over a hill by changing the level of water of the canal.