Secure Hashing Algorithm (SHA-1): A cryptographic hash function that produces a 160-bit hash value, which is typically rendered as a 40-digit hexadecimal number. SHA-1 is part of the Secure Hash Algorithm family designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST). It was widely used for security applications and protocols, including TLS and SSL, PGP, SSH, and IPsec. However, SHA-1 is no longer considered secure against well-funded attackers; as of 2005, theoretical weaknesses were discovered, and over time, practical attacks have demonstrated the ability to produce collisions (two different inputs that result in the same hash value). As a result, it has been recommended to transition to stronger hash functions such as SHA-256 or SHA-3.