Instantaneous speed is an object's rate of motion at a particular time period or moment. Recording the speed of a running cheetah exactly 13 seconds after its sprint began would be an example of instantaneous speed.
The instantaneous speed of an object should not be confused with the average speed. For example, a person who drives 60 miles in a single hour has an average speed of 60 miles per hour, but the instantaneous speed of the vehicle could vary greatly from one instant to another. Average speed is a measure for distance traveled in a given time frame, often referred to as the distance per time ratio.