This change in velocity can be:

* A change in speed: The object is moving faster or slower.

* A change in direction: The object is changing its path of motion, even if its speed stays the same.

* A change in both speed and direction: The object is changing both how fast it's moving and the direction it's moving in.

Here are some examples of acceleration:

* A car speeding up: The car's velocity is increasing, so it's accelerating.

* A car slowing down: The car's velocity is decreasing, so it's also accelerating (even though it's slowing down).

* A car turning a corner: Even if the car maintains a constant speed, its direction is changing, meaning it's accelerating.

* A ball thrown straight up in the air: The ball's velocity changes as it goes up and then comes down.

Key points to remember:

* Acceleration is a vector quantity, meaning it has both magnitude (how much) and direction.

* If an object is moving at a constant velocity (constant speed and direction), it's not accelerating.

* The acceleration of an object is caused by a force acting upon it.