From Minetest

Using refers to a special interaction with the pointed block or object.

By default, using is done by clicking with the right mouse button on the block/object you want to interact with.

Using requires the privilege “interact” which is given by default.

Note: Some items will have a special action when you press the “Use” key while wielding them.

In Minetest Game

By using, you can (for example):

Note: You can’t do any of these if you don’t have the “interact” privilege.

In other games

It depends. Just try out the “use” key on various blocks and objects and see what happens.

See also