For fast-paced sports it is important to make quick decisions so you can respond with the best appropriate action. This may be more important in boxing and combat sports than any other. An opportunity for a clean punch comes and goes quickly so a short response time for a fighter can mean the difference between a shot that lands and one that glances off. And that goes double for when it’s you who is the target.
So reaction time, simply, is a measure of how long it takes for an individual to react and respond to a stimulus. A stoplight turns red, which triggers a response for you to apply the brake. While the car needs time and space to complete the stop, the lag time before you actually decide to step on the brake could mean the difference between ending up in the middle of an intersection or stopping short of disaster.