Cryptographic hash functions are mathematical algorithms that transform input data into fixed-size strings of characters. They are designed to be one-way functions, making it computationally infeasible to reverse the process. Hash functions are fundamental to digital security, data integrity verification, and blockchain technology.
SHA-256 and SHA-512 are part of the SHA-2 family and are currently considered secure for cryptographic applications. SHA-384 offers a balance between security and performance. MD5 and SHA-1, while still useful for checksums and non-security applications, have known vulnerabilities and should not be used for password hashing or digital signatures.
Common use cases include password storage (with proper salting), file integrity verification, digital signatures, blockchain proof-of-work, and creating unique identifiers. Always use the strongest hash function appropriate for your security requirements.