Create a 128-bit string value from an arbitrary length input string. MD5 is a cryptographic hashing function, which by definition means that it is only computed in one direction and it is not possible to "reverse" it back to its original form.
MD5 (technically called MD5 Message-Digest Algorithm) is a cryptographic hash function whose main purpose is to verify that a file has been unaltered.
Instead of confirming two sets of data are identical by comparing the raw data, MD5 does this by producing a checksum on both sets and then comparing the checksums to verify they're the same.
MD5 has certain flaws, so it isn't useful for advanced encryption applications, but it's perfectly acceptable to use it for standard file verifications.
MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function MD4.
A message digest is a fixed size numeric representation of the contents of a message,
computed by a hash function. A message digest can be encrypted, forming a digital signature. Messages are inherently variable in size.
Message Digest is used to ensure the integrity of a message transmitted over an insecure channel
(where the content of the message can be changed). The message is passed through a
Cryptographic hash function. This function creates a compressed image of the message called Digest.