Pipes are basically the unsung heroes of a house — you kind of forget they're there, but they're vital to your everyday life. For example, if you like running water and dislike living with the contents of your toilet, you need them in good working order at all times. Unfortunately, that gets a bit harder during supercold weather. Even when you do your best to safeguard your home in Winter, including taking pipe protection measures, you can still get unlucky.
I'll never forget that scary January morning when we walked outside into a foot of snow, shivering in our bathrobes, and realized we'd forgotten to cover the outside spigot. When we turned it on, nothing happened. Oops. When you fail to cover outside faucets and adequately protect external pipes, the water (or sewage, blech) inside them can freeze. If the pressure on the pipe wall is sufficiently great, it may burst. That means, if your pipes do freeze, you need to get that water thawed as quickly as possible. Here's how.
As for us, we were very lucky. We left the faucet slightly open, covered it up, and checked it routinely until it began to flow again. No busted pipe. To this day, I am grateful to the guardian angel of plumbing that smiled down on us and saved us hundreds of dollars. It is said, however, that guardian angels of plumbing help those who help themselves — so get on it!