Definition
SHA-256, or Secure Hash Algorithm 256-bit, is a cryptographic hash function. It takes an input message of any size and produces a fixed-size 256-bit (32-byte) hash value. This process is one-way, meaning it's computationally infeasible to reverse the hash to find the original input. SHA-256 is crucial for data integrity and security in various applications. For instance, it's used to verify that a downloaded file hasn't been tampered with. If even a single bit of the input changes, the resulting SHA-256 hash will be drastically different. A common confusion is with older hash functions like MD5, which are now considered insecure due to collision vulnerabilities. SHA-256 is a widely accepted standard for secure hashing.