Block codes are a type of error-correcting code used in digital communication and data storage. They work by dividing data into fixed-size blocks and adding redundant bits to each block. This redundancy helps detect and correct errors that may occur during transmission or storage, ensuring the integrity of the data. One common example of block codes is the Hamming code, which can correct single-bit errors and detect two-bit errors. Block codes are essential in various applications, including computer networks, CDs, and QR codes, where reliable data transmission is crucial for performance and accuracy.