can someone tell me exactly what an intercooler does because i'm having an argument and need the exact definition

and also what the purpose of a blowoff valve is

 

intercooler: compressed air gets hot. The intercooler returns the intake air to near-ambient temperatures on a turbocharged car.

BOV: When the throttle plate closes, it creates a traffic jam for all the air that is being forced into the intercooler piping. the BOV opens when the throttle is closed to let that pressure out. Reduces stress on the turbo.

 

what he said plus....
intercoolers flow the intake air into small fins so that air flow can cool the air in the fins.....

BOV.... just think of the air being compressed into the motor. When the throttle body closes, where can this air go? If there wasn't a BOV, or if the BOV was set too tight, the air would be forced back towards the turbo (compressor surge) Imagine that turbo spinning at $%&$#@ rpm being hit with compressed air going the other way =P So the BOV allows the air to be purged back out....

 

thanks fellas