Every computer has a Ledger to pass a block from one to another. Is a Ledger built into every computer, or is it software that every operating system has? I am kind of confused about this? Any help would be appreciated!
So, each node is running compatible software that allows them to communicate with other nodes over the peer to peer network. Each node is responsible for maintaining their own ledger. You can think of it as storing your own database but ledgers are for financial transactions which is a more appropriate economic term.
Question. So all copies of the blockchain are updated instantly so we can say that each node is interacting live live with the blockchain?
I wouldn’t say instantly. Peers are constantly talking with each other as to the latest state of the blockchain. It takes time for blocks to propagate throughout the network so some nodes are more up to date than others. This depends a lot on network latency, geography, etc. This is part of the reason why BTC set the block time at 10 minutes to allow the network to catch up to the latest state of the blockchain.
I think ledger comes from accounting whereby we have two entries to every transaction that occurs ie debit or credit. However traditional ledger is being kept, maintained or updated by a central authority. But this Decentralized Public Ledger is being maintained by protocols or a set of rules. Its being verified by every node in the network. It’s a consensus ledger. The network has to agree on the validity of the transaction before it is incorporated into the ledger. So the ledger will always balance, the debit side and the credit side. There is no double spending. If you pay 1 btc, it means your wallet is now less 1btc and the wallet of the receiver is now 1 btc more. Your account also will be deducted with some very small transactions fees less than those charged by Visa or Mastercard
I think part of your question that hasn’t been addressed by the above is that having a ledger on your computer isn’t something native that comes with your computer when you buy it.
You have to download and install it first, sync it with the network, etc. Here is a step-by-step guide on how to become a Bitcoin node (i.e. maintaining an updated ledger): https://medium.com/coinmonks/how-to-run-a-bitcoin-full-node-in-6-simple-steps-a243189a5750
Thanks @aenhsaihan and @FaierPlay for answering. Just like they said, each node has a software implementation of the main code. They all sync and update to the longest chain. This is done when a miner mines a block. When a miner mines a block, he wants to immediately push his ledger to all surrounding nodes, so he can get the reward of the block. Its not instant, due to the latency of the internet.