SHA256, or Secure Hash Algorithm 256-bit, is a cryptographic hash function widely used in cybersecurity for data integrity and authentication. It transforms input data into a fixed 256-bit (32-byte) hash value, making it nearly impossible to reverse-engineer the original input or find two different inputs with the same hash. SHA256 is commonly used in digital signatures, SSL/TLS certificates, blockchain, and file verification. Its strong collision resistance and one-way nature make it a trusted standard for ensuring that digital files and messages have not been altered or tampered with during transmission or storage.