* Velocity is a measure of how fast an object is moving *and* in what direction.

* Acceleration is the rate of change of velocity.

Here are some examples:

* An object at the top of its trajectory in projectile motion: Imagine throwing a ball straight up. At the very peak of its flight, for a brief instant, the ball's velocity is zero (it stops moving upwards before falling back down). However, gravity is still acting on it, causing it to accelerate downwards.

* A car at a red light: A car stopped at a red light has zero velocity. But when the light turns green and the car starts moving, it accelerates from zero velocity.

Key takeaway: Acceleration is about *changes* in velocity, not just the velocity itself. An object can be accelerating even if it's momentarily stationary.