What is secp256k1, Bitcoin's elliptic curve?
The curve y² = x³ + 7, whose maths turns a private key into a public key that ordinary computers cannot reverse efficiently.
Bitcoin uses an elliptic curve called secp256k1, from a 2000 standard by an industry group. Its numbers were chosen in a predictable way, not from an unexplained seed.
It isn't one of the NIST curves that many websites use.
References
- Certicom Research, Standards for Efficient Cryptography Group, “SEC 2: Recommended Elliptic Curve Domain Parameters, version 2.0”.