a service for exploring blockchain. Through the block explorer you can track Bitcoin transactions, check block and transaction info, amounts etc.
a transfer of bitcoins from one wallet to another. Transactions are cryptographically secured and become legitimate as soon as they are included into the block. The process of being included into the block is called the confirmation process. Within the Bitcoin cryptocurrency, a transaction can be considered confirmed after 6 confirmations. It takes on average 10 minutes for a transaction to be confirmed. This process was undertaken in order to avoid double-spending attack.
a transaction that has not been included into the blockchain yet, but each node is informed about this transaction. Transaction can be left unconfirmed for a long period of time (not included into the blockchain) because of the following reasons:
the amount of bitcoins which is collected from the bitcoin transaction. The fee collected through the transaction goes to miners to encourage them to keep mining. A miner can include such amount of transactions that he prefers, thus, he can automatically increase his reward. Within the Bitcoin cryptocurrency, the user can set up a fee that he prefers, but he needs to take into account that if it is too small the transaction can stay unconfirmed for a long time.
a storage that permanently records the Bitcoin Network Data. These units of code consist of block header and transactions' merkle tree . Each block is linked with the previous one and takes origin from the genesis block. The data contained in the Bitcoin block cannot be modified and deleted.
an identifier of about 27 - 34 alphanumeric symbols. (Technically speaking, it is a 160-bit hash). It begins with a 1 or a 3. With a wallet service you can create an address free of charge. In order to reach a high level of anonymity,a user needs to generate an address for each new transaction.
the very first block in the blockchain.
a block which is not included into the valid blockchain. It occurs when two or more miners simulataneously find a block. In this situation only one block can be confirmed and stored in blockchain while the other one will be rejected by the network, thus the finder will not be rewarded with the coins that the block contained.
a number of blocks between the block and the genesis block which height is 0.
a unique identificator of transactions and blocks. Technically, it is a complex mathematical function that is used in block verification during the mining process. After a valid block hash is calculated, the miner gets fixed reward with transaction fees included into the block.
80 bytes of block data that include Block version number, hash of the Previous Block, hash of the Merkle Root, Time, Bits and the Nonce.
an attack when the same coins are used in more than one transaction.
an attack when a miner or a mining pool extend its computing resources to the level that it becomes possible to control 51% of the Bitcoin Network computing power, thus block generation is only up to the one player giving no chance to the others.
memory pool, files with data about valid transactions that are not included into the block as they are unconfirmed.