There are seven tenses in Greek:-
Present, Imperfect, Aorist, Future, Perfect, Pluperfect, Future Perfect.These tenses express both aspect (the kind of action) and time (when the action takes place), though aspect is often more primary than time in many moods outside the indicative.
Those tenses which denote present or future time are called Primary Tenses. Those tenses which denote past time are called Secondary Tenses.
Since the time denoted by a tense varies with the particular use of the tense and the mood in which it occurs, no fixed or absolute line of division can be drawn between the two classes of tenses.… Learn Koine Greek