Error correction attempts to detect and correct errors in systems that transport information. Many systems use error correction. From proof readers of books through to biological systems that check DNA replication. It is very important in the domain of data transfer over computer networks. Error detection methods are the bedrock of error correction. Errors need to be identified before any action can be taken. Some networking protocols include extra information within data packets that can be used to repair the data if required. There are many ways to do this. Sometimes the error correction method is simply to ask the sender to try again until no errors are detected.