Usually is used when something happens enough times that you can predict the outcome with a good chance of being right. And if what usually happens doesn't, it's shocking. > He usually comes to class on time. From this sentence, you know he comes the class on time so many times, that you can predict that next class he will be on time again. > He usually comes to class on time, but he's not here. I hope he's OK. From this sentence, you see how his absence from class is shocking and caused you to worry. Often is used when something happens frequently but not necessarily predictable. It occurs 'often but not always'. > It rain here often. From this sentence, you know it rains there a lot but there's no reason to predict that it will rain there tomorrow. Usually and Often used in a conversation: Person 1: Our teacher assigns us homework often. Person 2: You're lucky. My teacher usually assigns us homework. Out of 10 classes we were assigned homework 9 times. Now, I just assume that I'll have homework. Person 1: Out of 10 classes we were assigned homework 6 times. We get homework often but not always. Both Person 1 and Person 2 are frequently assigned homework by their teachers. However, Person 2 is assigned homework so many times that it becomes predictable.

Yes, it is related to time. Often when something is done or happens very less than normal. Usually is when something is done or happens a lot. Ex: 1. I often take the bus while going to school. (~means that you don't go to school by bus everyday but when necessary, which is NOT a regular thing to do.) 2. I usually walk to my school. (~means that you walk on your way to school almost everyday, and is a regular procedure.) Smash those two sentences and you get something like this!-> >> I often take the bus to school because I usually prefer walking. Hope that was a bit easier to grasp now...^_^