Here's a breakdown:

* Velocity is a combination of speed and direction.

* Acceleration is the rate of change of velocity.

Therefore, an object accelerates when:

* It speeds up: The object's velocity increases.

* It slows down: The object's velocity decreases.

* It changes direction: Even if the object maintains the same speed, a change in direction means its velocity is changing.

In summary: Any change in the object's speed or direction results in acceleration.