A hash function takes an input (or 'message') and returns a fixed-size string of characters, which is typically a hexadecimal number. It's a one-way process, meaning you cannot reverse it to obtain the original input. MD4 (Message Digest Algorithm 4):MD4 is a cryptographic hash function that produces a 128-bit hash value, typically expressed as a 32-character hexadecimal number. It is considered insecure and vulnerable to collision attacks. MD5 (Message Digest Algorithm 5):MD5 is another cryptographic hash function that produces a 128-bit hash value, often represented as a 32-character hexadecimal number. Like MD4, MD5 is also insecure due to vulnerabilities, and it is not recommended for cryptographic purposes. SHA-1 (Secure Hash Algorithm 1):SHA-1 produces a 160-bit hash value, usually represented as a 40-character hexadecimal number. It was widely used but is now deprecated due to vulnerabilities, and collision attacks have been demonstrated. SHA-256, SHA-384, SHA-512 (Secure Hash Algorithms):These are part of the SHA-2 family of hash functions, providing hash values of different lengths (256, 384, and 512 bits, respectively). They are widely used and considered secure for various applications. HMAC (Hash-based Message Authentication Code):HMAC is a specific construction for creating a message authentication code using a cryptographic hash function along with a secret key. It enhances the security of the hash by incorporating a key into the calculation. Argon2:Argon2 is a key derivation function designed for password hashing. It is resistant to GPU and ASIC attacks, making it a suitable choice for securely hashing passwords. Whirlpool:Whirlpool is a cryptographic hash function that produces a 512-bit hash value. It is not as widely used as SHA-2, but it is considered secure. CRC32 (Cyclic Redundancy Check):CRC32 is a non-cryptographic hash function commonly used for error-checking purposes. It's fast but not suitable for cryptographic applications due to its vulnerability to collision attacks.