What is address reuse, and why avoid it?

Wallets can make a fresh address for every payment. Reusing one makes its payments easier to link, although the blockchainBlockchainBitcoin's shared record of every payment since 2009, stored in blocks that each link to the one before — which is what makes it a chain. alone does not prove who controls it.

Public-key exposure depends on the address type. Legacy and SegWitSegWitSegregated Witness: a 2017 upgrade that moved signatures into a separate part of each payment, making room for more payments. v0 addresses normally reveal the key when spending, while TaprootTaprootA 2021 upgrade that added Schnorr signatures and addresses starting bc1p, making complex payments cheaper and more private. output keys are already visible. Exposed keys would be among the first at risk if quantum computersQuantum computer (qubit)A computer that uses quantum physics to solve some problems far faster than ordinary ones. Its working parts are called qubits. ever become powerful enough to break them.