Definition
JWS (JSON Web Signature, RFC 7515) is the cryptographic signing standard underlying JWTs — a payload signed with an algorithm declared in the header, serialized into compact or JSON form.
In more depth
Every JWT is technically a JWS (or a JWE — see below). The JWS specification defines how to combine a header + payload + signature into a verifiable token. Signature algorithms include HS256/384/512 (HMAC), RS256/384/512 (RSA), ES256/384/512 (ECDSA), and EdDSA.
A JWS can be either signed-only (the payload is visible) or part of a JWE (where it's also encrypted). JWT is the most common application of JWS.
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