There are three major approaches to defining the essence of perfective forms in English:
The category of perfect is a peculiar tense category, i. e. a category which should be classed in the same list as the categories "present" and "past".
The category of perfect is a peculiar aspect category, i. e. one which should be given a place in the list comprising "common aspect" and "continuous aspect".
The category of perfect is neither one of tense, nor one of aspect but a specific category different from both.
The category denotes correlation of the action expressed by the finite verb to some moment in the past, present or future.
This category is based on the opposition “perfect vs. non-perfect”. The opposition is privative in the plane of expression, however, it is not so easily neutralized in the plane of content. Since the opposition is not easily neutralized in the present tense, it is equipollent, but it can easily be neutralized in the past. Therefore, it should be considered privative-equipollent.