Definition:The concept/law in which an event occurs only after its cause triggers it to do so.
It can be understood as a relation between two events in which the second one is the consequence of the first one.
Causality is also the relation between a set of factors (causes) and a phenomenon. Anything that affects an effect is a factor of that effect. A direct factor is a factor that affects an effect directly, that is, without any intervening factors. (Intervening factors are sometimes called "intermediate factors".)