The definition of cause and effect is when one event or actor (the cause) produces a result, impact, or change (the effect). The relationship between the first event and the result is said to be a causal relationship.
In order for a causal relationship to occur, there are three criteria that must be met. First, the cause has to occur before the effect happens. Second, the cause and effect must be reproducible. Namely, every time the cause occurs, the effect happens, and the effect does not happen in the absence of the cause. The third criterion is that the effect is actually due to the cause rather than to some other event or cause.