Go and Come Back

If you mean in terms of when to use which, this might help:

Imagine you and your friend are standing at Point A. You decide to walk toward Point B, about 100 yards away, while your friend stays at Point A. Once you get to Point B, you decide to return to Point A.

From YOUR perspective, you would ‘go back’ to Point A, because that’s where you were before and you’re now leaving Point B behind you. But from YOUR FRIEND’s perspective, you would ‘come back’ to Point A, because he never left it and you’re walking TOWARDS him to return to Point A.

If you then BOTH decided to walk to Point B together, you would BOTH be ‘going back’ to it (even though your friend didn’t go with you the first time) because you’re both leaving the point where you are to go somewhere else. However, if ANOTHER friend showed up at the Point A you left, and once you got to Point B you decided to return to him at Point A, you would BOTH be ‘going back’ to meet your other friend. But from your other friend’s perspective you would BOTH be ‘coming back’ to him, because again, he’s seeing you walking to where he is.

Hope that makes sense. :)