Quote Originally Posted by ShakeyX View Post
I think the way I was taught to use perfective/imperfective is like if you read a book in the past but didn't finish it (you were reading) then you use the imperfective past, if you completed the book, (you read it) then you use the perfective past. This can be translated to the future tense where you can say I will be reading, I will read and complete.
Imperfective aspect doesn't imply the action wasn't completed, it just doesn't focus on this action as a certain point in time with a certain result. More as a repeated activity, or a prolonged activity that "was taking place" for some time. Also it is used to refer to action in general, i.e. when you ask questions whether some activity was there at all, or not, you use imperfective ("Ты читал эту книгу?" is a good example)