Definition: MD5, technically called MD5 Message-Digest Algorithm, is a cryptographic hash function.
The MD5 cryptographic hash function is most often used to verify that a file has been unaltered by comparing the checksums created after running the algorithm on two seemingly identical files.
MD5 has certain flaws and so it isn't useful for advanced encryption applications but it's perfectly acceptable to use for standard file verifications.
SHA-1 is another commonly used cryptographic hash function.
Examples:
"I generated checksum values on an important file I backed up to ensure that everything went OK. I wasn't concerned about advanced malicious changes so I just used the MD5 cryptographic hash function."
