Causality (also referred to as 'causation', or 'cause and effect') is the agency or efficacy that connects one process (the cause) with another (the effect), where the first is understood to be partly responsible for the second. In general, a process has many causes, which are said to be causal factors for it, and all lie in its past. An effect can in turn be a cause of many other effects, which all lie in its future.