Iterative decoding is a technique used in the field of coding theory and information theory to decode error-correcting codes. It involves repeatedly passing messages between the decoder and the received signal in order to gradually improve decoding accuracy. In iterative decoding, the decoder makes an initial estimate of the transmitted codeword based on the received signal. It then passes messages back and forth between the decoder and the received signal, using techniques such as belief propagation or the sum-product algorithm, to refine the estimate of the codeword. This iterative process allows the decoder to incorporate more information and make more accurate corrections to decoding errors, ultimately leading to improved overall decoding performance. Iterative decoding is commonly used in applications such as digital communication systems, where reliable and efficient error correction is essential.