A Bitcoin confirmation signifies the verification of a transaction by the network, achieved when a transaction is included in a block on the blockchain. Each subsequent block added to the chain grants the transaction an additional confirmation, reinforcing its validity and reducing the likelihood of reversal. 

Upon initiating a Bitcoin transaction, it is broadcast to a network of nodes awaiting validation. This validation is accomplished by miners who solve complex mathematical puzzles to include the transaction in a new block. When a transaction is included in a newly mined block, it receives its first confirmation. With each subsequent block added to the chain, the transaction receives additional confirmations, further solidifying its status within the network.

The essence of blockchain confirmations lies in the assurance they provide. A higher number of confirmations significantly diminishes the probability of a transaction being reversed, ensuring unparalleled security. For instance, in the Bitcoin network, a transaction is generally considered irreversible after six confirmations. This convention stems from the network's design, which makes altering a transaction exponentially harder with each new block added to the chain.