* Acceleration is the rate of change of velocity. This means that if an object is accelerating, its velocity is either increasing, decreasing, or changing direction.

* Constant acceleration means the velocity changes by a constant amount over each unit of time.

* Variable acceleration means the velocity changes by a different amount over each unit of time.

Here are some examples:

* Car speeding up: The car's velocity is increasing.

* Car slowing down: The car's velocity is decreasing.

* Car turning a corner: The car's velocity is changing direction, even if its speed remains constant.

Important Note: Acceleration is a vector quantity, meaning it has both magnitude (how much) and direction. Therefore, a change in velocity can be due to a change in speed, a change in direction, or both.