A Reaction Time Test checks how a person responds to a cue such as a noise or flash. The individual waits for the signal and then hits a button or clicks a mouse. The Online Reaction Time Test measures, in milliseconds, the time between the cue and the person's action. This reveals how well the mind and body coordinate. Reaction Tests in athletics, psychology, and healthcare aim to boost safety and performance. Also, training can cut down reaction times, which is key for driving, sports, and gaming.