The essay.

I've always been an avid reader of essays, and I think my fondness for them is what helped me make the leap from the lake of fiction to the sturdier realm of travelogues, reportage and history. Yet coming from fiction first has its advantages. One can spot the yarn buried within, the fable brandished as fact. Once fiction makes a cameo in an informative piece, it is up to us, the readers, to judge what master it serves.

Here's a good book review on a compliation of essays.