Most basements are equipped with a sump pump that is installed in a sump pit. Through drainage made under and around foundation walls underground water is directed into the sump pit. When water in the pit rises to a certain level sump pump starts ejecting it up and away from your house. Sump pump battery backup is an additional pump that fits next to the main sump pump and turns on during a power outage, main pump failure, or when the main pump can't keep up with the inflow of water. Sump pump backup will also let you know with its alarm that the main pump has failed.
There are also backup sump pumps that are powered by generators. It is a good idea to get one instead of a battery backup when you travel a lot or when you live on flood hazard property. This system helps to ensure that your basement is dry all the time.
If you have a sump pump, it probably discharges outside. Snow and ice can block the opening and cause it to freeze. When this happens your pump will be running and the water can't get out, causing your basement to flood. Installing an ice guard on your discharge line will prevent this problem.