question about the AC thing in the engine.

I don't know whats it called but its behind the Coolant reservoir and next to that square thing behind the battery, anyhow it gets wet everythime i turn on the A/C, after driving water would drip underneath the car. And today i didn't turn on the A/C but there is still water on top of that shiny metal thing with hoses around it. IS this normal? Do you know what i am talking about

The shiney thing is called the Accumulator and yes it will sweat.

If you turned on the Defrost, it turns on the AC system even if you want to clear the windshield with warm air.