Volvo: low compression in 740 turbo, head gasket, eplain

Question
my car died and i have taken it to a mechanic who said that the compression is too low to even start the car.  he didn't eplain what that meant.  what does this mean?  what will i have to fix?  
thanks!

Answer
Alix,
Worn rings are the cause of low compression, but so is a leaking head gasket or a burnt valve. Without seeing the car and doing some tests I can not be sure what is the exact cause of the low compression. I would say that you need a second opinion. If the engine is in fact loosing compression because of worn rings a complete engine overhaul would be needed.