CCA (Cold Cranking Amps) is the number of amps the battery will supply for 30 seconds at zero degrees before its voltage drop too low.
MCA (Marine Cranking Amps) is essentially the same as CCA except in this case it refers to the number of amps the battery will supply for 30 seconds at 32 degrees before the voltage drops too low to use.
RC (Reserve Capacity) is the number of minutes a battery will last under a 25 amp draw (higher rating in minutes = longer the battery will last). This rating is a better measurement for the capacity of a deep cycle battery.
AH (Amp Hours) rating is how much amperage is available when discharged over a 20-hour period (higher amp hour = the longer the battery will last).
