How transactions of Bitcoin work?
Bitcoin operates on a decentralised ledger called the blockchain, which is maintained by nodes participating in the network.
When transactions are made, they are grouped into blocks. These blocks are then validated and added to the blockchain through a consensus mechanism known as Proof-of-Work (PoW). This mechanism requires that a majority of the network's computational power (not necessarily a majority of nodes) agree on the ledger's state.
The acceptance of blocks and transactions contained is dependent upon two races. The first is to solve the computation, and the second is to propagate the block to a majority of the network. The reward (subsidy+fees) is not realized for 100 blocks.