Reaction time is the interval between the presentation of a stimulus and the response to it. This can involve simple actions, like pressing a button when a light turns on, or more complex responses, such as dodging an object. It is an important measure in various fields, including sports, psychology, and neuroscience, as it reflects how quickly an individual can process information and act. Factors affecting reaction time include age, fatigue, and distractions. Generally, younger individuals tend to have faster reaction times compared to older adults. Additionally, practice and familiarity with a task can improve reaction time, making it a crucial aspect in competitive environments like sports and video games.