In drama, a protasis is the introductory part of a play, usually its first act. The term was coined by the fourth-century Roman grammarian Aelius Donatus. He defined a play as being made up of three separate parts, the other two being epitasis and catastrophe. In modern dramatic theory the term dramatic arc has substantially the same meaning,^[1] though with slightly different divisions.

This article relies largely or entirely on a single source. (August 2020)