MD5, or Message-Digest Algorithm 5, is a widely used cryptographic hash function that produces a 128-bit hash value from input data. It is commonly used to verify data integrity, ensuring that files or messages have not been altered. For example, when downloading software, an MD5 hash can confirm that the file is exactly what the developer intended. Despite its popularity, MD5 is no longer considered secure for cryptographic purposes due to vulnerabilities that allow for hash collisions, where different inputs produce the same hash. As a result, many organizations have shifted to more secure alternatives like SHA-256 for protecting sensitive information.