I remember reading once that a writer shouldn't rely too much on dialogue for telling a story. Because of this the technique has always been something that plays on my mind whenever I use it to get information across. But how do we know when to use it and when to use narrative? If, for example, I wanted to give a little back story or history to a character, what dictates whether I do this through dialogue or narrative? I find it infinitely easier to do this through dialogue, but for this very reason I often force myself to do it through the narrative where I'm less comfortable. So, what's the rule of thumb? When is it okay to give back story through dialogue? Is it fair to say it's acceptable only if such a conversation would take place in the real world?