Liens - mortgage, tax liens (for unpaid taxes), mechanics liens (for unpaid work on your house), judgement liens (court ordered), child support liens (for unpaid child support), etc.
Depending on the circumstances, liens follow the land and you can't sell until the liens are paid. Before you keep the house, it's imperitive to know if you have any liens against your house.
How do you find out if you have liens on your house? Watch video!