The prefix "pre-" means "before" and is used to indicate that something happens prior to another event. For example, in the word preview, it refers to seeing something before the main event, like watching a trailer before a movie. This prefix helps us understand the timing of actions or events in relation to one another. Another common use of "pre-" is in the word pregnancy, which describes the period before a baby is born. During this time, many changes occur in the body as it prepares for childbirth. Understanding "pre-" helps us grasp the sequence of events in various contexts, from science to everyday life.