It is mainly used for security in database systems. The algorithm generates a unique hash code for every piece of data (strings, text etc.). Any change to the data, either deliberate or accidental, will mean the hash code will also change. By comparing the codes, it is easy to see if a change has been made. MD5 was invented by Ron Rivest of the Massachusetts Institute of Technology in 1991. An MD5 hash code provides a 32-digit hexadecimal number. By 1996, methods were developed to break the security of an MD5 algorithm. This was done by getting another program to make the same hash number for different sets of data. MD5 is no longer considered acceptable for protecting against intentional malicious changes to data, but it is still considered OK to protect from accidental changes, for example single-bit changes caused by noise on a network connection. An MD5 hash could look like: 9c677286866aad38f8e9b660f5411814. This is the hash of the string "Wikipedia".