A cryptographic protocol for creating Schnorr-based multisignatures in Bitcoin. An improvement over the original MuSig protocol, MuSig2 offers greater privacy, scalability, and flexibility when compared to standard multisignature by enabling a group of signers to produce a single signature representing their collective consent for a specific transaction.

In MuSig2, each signer's key material is confidential and has veto power, meaning the transaction can only be approved if every signer in the group agrees. This allows for greater resistance against certain attacks, such as key cancellation, as well as rogue key and replay attacks.

MuSig2 is n-of-n, however, when paired with Taproot, you can simulate a t-of-n threshold signature. Consider 2-of-{A, B, C}, then this is equivalent to 2-of-{A,B}, 2-of-{A,C} or 2-of-{B,C}. These are all 2-of-2 MuSigs, meaning you can construct your Taproot output such that the most likely of the three spending paths becomes the Taproot key path, and the other two get included in the Taproot script path.

More information on MuSig2 can be found reading its official whitepaper and watching the visual explainer below.