What is it called when the subject of a sentence performs action?

When the subject of a sentence performs the action, it's called an active voice.

Here's an example:

* Active voice: The dog chased the ball. (The subject, "dog," performs the action of "chasing").

In contrast, passive voice occurs when the subject is acted upon:

* Passive voice: The ball was chased by the dog. (The subject, "ball," is acted upon by the dog).