Yes, it's my content...
https://www.reddit.com/u/Fabs_-/s/sHSWMLSrYuBitcoin is a digital currency that operates on a decentralized network of computers, called nodes. Decentralized means that there is no central entity that controls the network, and thus, no central authority which assembles the state of the ledger, known as the blockchain. Instead, Bitcoin uses a mechanism called “emergent consensus”, which is achieved through nodes respecting the same rules, allowing thousands of individual nodes to assemble the same local copy of the blockchain, without being dependent on a central authority.
A transaction is added to the blockchain as part of a block, which essentially records a batch of new transactions into the blockchain.
Once a transaction is broadcast to the network, nodes independently verify the transaction against the consensus rules first, after which it's verified against their policy rules, which are a set of rules or conditions that are defined by the individual node. Once validated, the transaction is temporarily stored into a node’s mempool, where it waits for a miner to take it along with other validated transactions, and aggregate it into a candidate block, which is a block that is not yet confirmed nor added to the blockchain.
The candidate block then enters the process of “mining”, which refers to the computational and energy-intensive task of finding a "valid" hash, also known as a Proof-of-work, which is made-up of the candidate blocks contents (transaction data(inputs and outputs), block header) + a random input. The difficulty of finding a valid hash changes approximately every two weeks or 2016 blocks through a mechanism called the “difficulty adjustment”. This mechanism changes the conditions depending on the amount of time it took to calculate the hashes during the former epoch, as well as total hash rate available in the network.
Once a valid hash has been found, the miner broadcasts the candidate block + hash to the network, where nodes independently verify the block, its contents and the hash against the consensus rules, which are the fundamental, unchanging rules that are hard-coded into the blockchain’s protocol and are agreed upon by the entire network, they determine how blocks are created, validated, and added to the blockchain. Once the block is validated, it's added to the node's local copy of the blockchain and propagated across the network to its peers.