Tezos supports the use of multiple public-key signature schemes in order to increase combability with available cryptographic tools and libraries. The public key hash reveals what signature scheme it has been derived from by its prefix. In Base58 encoding the first 3 characters shows what signature scheme have been used and in the binary encoding this is represented by a 8-bit tag.
An EdDSA signature scheme that uses SHA-512 and Curve25519. This is the most commonly used signature scheme in Tezos.
Secp256k1 describes the parameters used in the ECDSA algorithm. The default signature scheme in Bitcoin.
A prime elliptic curve standardised by NIST. Also known as secp256r1 and considered a sibling to secp256k1.