Can you store a lawnmower outside?

A gas mower in a yard in front of a border with a wooden shed behind .

Not all of us are blessed with a lot of backyard storage. Perhaps you can't afford to build a shed, or your HOA won't allow one, but in the end you're left with a lawnmower and nowhere to keep it. 

This has led many to wonder if they can just leave their mower outside. I've found that you can, but I don't recommend it.