Iterative decoders are algorithms used in decoding error-correcting codes, such as turbo codes and LDPC codes. These decoders use an iterative approach where the decoder makes several passes through the received data, refining its estimate of the original message with each iteration. The basic idea behind iterative decoders is to exploit the correlation between the bits in the received signal to improve accuracy in decoding. By passing information back and forth between different decoding stages or components, iterative decoders can achieve near-optimal performance in terms of error correction. Iterative decoders are commonly used in communication systems, such as wireless networks and optical communication systems, where reliable transmission of data is essential. They have proven to be highly effective in improving the efficiency and reliability of data transmission over noisy channels.