Glossary

User-Activated Soft Fork (UASF)

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A User-Activated Soft Fork (UASF) is an update or change to the Bitcoin network’s protocol initiated by users or nodes, who integrate new code into their Bitcoin implementations and demonstrate their acceptance of the change so that miners and other users can implement the same changes knowing they will maintain consensus. Since the update is a soft fork, updating is not required because the changes to the protocol are backwards compatible. If a node does not update, they are not harmed at all.

Related Terms
Soft fork
A soft fork is a backwards-compatible change to a project's source code, meaning not every node must adopt the upgrade to stay in consensus.
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Bitcoin node
A node is a member of a network that interacts with other nodes. Bitcoin nodes store and validate the blockchain and relay blocks and transactions.
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Consensus
Consensus is the method of coordination between participants in a decentralized system, both on changes to the Bitcoin protocol and on the chain's state.
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Miner-Activated Soft Fork (MASF)
A Miner-Activated Soft Fork (MASF) is a soft fork which is activated by miners who begin mining blocks under the updated ruleset.
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Hard fork
A Hard fork is a consensus change that is not backwards compatible. It requires that all nodes on a network upgrade in order to avoid splitting the network.
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