ECC is Error Correction Code or Error Correting Code.
Basically it is a way to make sure that the data remains free from one bit errors. One bit errors are the most common. ECC cannot fix more that a one bit error but anything more than a one bit are extremely rare.
Your CPU uses ECC in its cache.
This is a basic explination. If you need more info or something more specific just let us here in the THGC know.
Yeah. Also ECC RAM is a type of memory that includes special circuitry for testing the accuracy of data as it passes in and out of memory. If you are not setting up a server or not running data critical programs, then it's really not necessary to spend the extra $ for ECC memory. You won't notice any difference between the ECC and non-ECC ones.