ECC definition

In data integrity, ECC (Error Correction Code) is a method that enables a system to detect and correct a limited number of errors within a certain section of data in storage. It most commonly refers to RAM/SDRAM modules which, often with an extra chip or two, employs some encoding scheme to reliably detect and correct one or few "bit flips" within a word line (e.g. 1 bit for each 64) and perhaps detect more errors while alerting the system and triggering a fail-safe stop. ECC is thus used to help minimise potentially catastrophic errors or corruption, at the cost of higher prices and a small performance penalty. Some hard drives, solid state drives and other storage devices also use ECC internally and externally to correct or at least detect most errors, while some buses/data transport interfaces can also use them to correct received data or request retransmission.

In short, ECC can fix minor corruption and often (if not always) detect major errors.