What is under insurance and over insurance?

Not sure if you meant over insured and under insured. Basically there is a provision in homeowners and condo owner policies called a Co-Insurance penatly if you are not insured to 80% of replacement cost (not market value) of the home. If you are insured less than the 80% (under insured), you will not get you complete coverage limit but a reduced amount.

Over insured is a little different. Lets say you insure your home at $100,000 and it would only cost $80,000 to replace. The insurance company would only pay the $80,000 but your premium paid was based on the $100,000 amount. If you are over insured, you will over pay for coverage. **Some states are "Valued Policy" states and you would get the full $100,000.

Just a quick answer, but I hoped it helped.