In land reclamation, people make sure that there is more land. To do this, they drain a piece of the sea or a lake. Land reclamation can also mean making unusable land usable, for example land in the desert.
In the past, land was reclaimed mainly because people wanted to farm there. Today there is another reason: houses can be built on the new land. People live or work there. Sometimes it is also about an airport for which there would otherwise be no space.
The new land often lies directly on the old, previous land. This new land is called a koog or, in the Netherlands, a polder. Other new land is surrounded by water on all sides and is thus an island.