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MD5 is a type of algorithm that is known as a cryptographic hash algorithm. MD5 produces a hash value in a hexadecimal format. This competes with other designs where hash functions take in a certain piece of data, and change it to provide a key or value that can be used in place of the original value.
With the development of various hash algorithms, experts have noted that engineers found MD5 to have serious weaknesses in terms of not being "collision resistant." A collision happens when two hash values are found to be similar or the same. To work correctly, each individual hash value has to be unique. Because this functionality is needed for popular authentication protocols like Secure Sockets Layer (SSL), MD5 has often been replaced with other types of hash algorithms.
Security engineers and others are familiar with long lists of hash algorithms with different properties. MD5 and other types of hash algorithms are often referred to as "message digest" functions.The idea here is that a hash "digests" an original value and outputs a replacement value that is significantly different from the original. Hashes have several main uses in security and database efficiency, related to the use of replacement values in searches and in data storage.