Default simply means that the owner has not paid his mortgage in a timely manner. He could be 2 months in arrears or he could be at the door of foreclosure. If you hear the term "short sale" it means that the owner owes more than the value of the home and the bank would have to approve the sale price.
A property in default means that the mortgage holder failed to live up to their obligation. This entitles the Lender to start foreclosure proceedings and call in the loan.
I hope this answers your question.
The very best of luck to you!
Michael D Delp
4802 Old Bethlehem Pike,
Telford Pa. 18969