QR Code has error correction capability. Data can be restored even if the symbol is partially dirty or damaged. A maximum 30% of codewords*1 can be restored*2.

*1: A codeword is a unit that constructs the data area. In the case of QR Code, one codeword is equal to 8 bits.
*2: Data restoration may not be fully performed depending on the amount of dirt or damage.

Related page: Error correction feature