A stage of an activity, process, or period is one part of it.

In a theatre, the stage is an area where actors or other entertainers perform.

You can refer to acting and the production of plays in a theatre as the stage .

If someone stages a play or other show, they organize and present a performance of it.

If you stage an event or ceremony, you organize it and usually take part in it.

You can refer to a particular area of activity as a particular stage, especially when you are talking about politics.