Bitcoin: Difference between revisions
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When a transaction is first acknowledged in a block, it receives one confirmation. The transaction itself is only acknowledged once, but blocks themselves are acknowledged repeatedly as time passes and the chain grows. Each time that first block is acknowledged by future blocks, the transaction is considered to have received another confirmation. After six confirmations, the Bitcoin client switches from showing "unconfirmed" to "confirmed". Although a transaction is technically "confirmed" after a single confirmation, the client avoids reporting it until several confirmations later, just to ensure that it is overwhelmingly likely that the transactions are part of the main block chain rather than an orphaned one, and more importantly, practically impossible to reverse. | When a transaction is first acknowledged in a block, it receives one confirmation. The transaction itself is only acknowledged once, but blocks themselves are acknowledged repeatedly as time passes and the chain grows. Each time that first block is acknowledged by future blocks, the transaction is considered to have received another confirmation. After six confirmations, the Bitcoin client switches from showing "unconfirmed" to "confirmed". Although a transaction is technically "confirmed" after a single confirmation, the client avoids reporting it until several confirmations later, just to ensure that it is overwhelmingly likely that the transactions are part of the main block chain rather than an orphaned one, and more importantly, practically impossible to reverse. | ||
Eventually, the block-chain contains the cryptographic ownership history of all coins from their creator-address to their current owner-address.<ref name="bbe">{{cite web |url=http://blockexplorer.com/ |title=Bitcoin Block Explorer }}</ref> Therefore, if a user attempts to reuse coins he had already spent, the network will reject the transaction. | Eventually, the block-chain contains the cryptographic ownership history of all coins from their creator-address to their current owner-address.<ref name="bbe">{{cite web |url=http://blockexplorer.com/ |title=Bitcoin Block Explorer |archivedate=dd mm yyyy }}</ref> Therefore, if a user attempts to reuse coins he had already spent, the network will reject the transaction. | ||
The whole history of transactions must be stored inside the block chain database, which grows constantly as new records are added and never removed. By design, some but not all users need the entire database to use Bitcoin - some users only need the portion of the database that pertains to the coins they own or might receive in the future. Presently, the database is small enough (less than 200 MB as of April 2011) that all users of the Bitcoin software receive the entire database over the peer-to-peer network shortly after running the software the first time. | The whole history of transactions must be stored inside the block chain database, which grows constantly as new records are added and never removed. By design, some but not all users need the entire database to use Bitcoin - some users only need the portion of the database that pertains to the coins they own or might receive in the future. Presently, the database is small enough (less than 200 MB as of April 2011) that all users of the Bitcoin software receive the entire database over the peer-to-peer network shortly after running the software the first time. | ||
