I was inspired by a recent reddit post to write my own description of the various single-sig output formats in Bitcoin. I’ll be covering only output types that make use of a single signature. “Legacy Outputs” aka P2PKH Pay to Public Key Hash was the first output type that got an address standard. Addresses for P2PKH outputs start with “1” and use the Base58Check encoding. The address encoding provides a checksum and represents a shorthand to communicate recipient information—which improved the UX over the prior situation which required the sender to handle the recipient’s full public key or non-standard output script to send a transaction.

This article was originally published on my medium page on 2020-08-18. This article was amended on 2020–12–20 to improve the description of the P2TR output scripts. Thanks to Matthew Zipkin, for pointing out the prior imprecision. The Bitcoin community has been abuzz for a few years about bringing Schnorr signatures to Bitcoin. Since then, the idea has evolved into three formal Bitcoin Improvement Proposals: ‘BIP340 — Schnorr Signatures for secp256k1’, ‘BIP341 — Taproot: SegWit version 1 spending rules’, and ‘BIP342 — Validation of Taproot Scripts’.