SHA-256 vs MD5: what is the difference?

MD5 and SHA-256 are cryptographic hash functions: they turn any input into a fixed-length fingerprint. They differ in output size and, crucially, security — MD5 is considered broken, while SHA-256 is a current standard.

What a hash is

A hash function maps arbitrary data to a fixed-size digest. The same input always gives the same digest, a tiny change gives a completely different one, and you cannot reverse the digest back to the input. Hashes are used for integrity checks, deduplication, and (with salting) password storage.

Why MD5 is broken

MD5 produces a 128-bit digest and is fast — but researchers can now craft two different inputs with the same MD5 (a collision) cheaply. That makes it unsafe for signatures or anything security-sensitive. It is still fine as a non-security checksum for detecting accidental corruption.

SHA-256 as the default

SHA-256 (part of the SHA-2 family) produces a 256-bit digest with no practical collision attack. It is the default for certificates, file integrity, and blockchains. For passwords specifically, use a slow, salted algorithm like bcrypt or Argon2 — plain SHA-256 is too fast.

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