Bitcoin Mining is a peer-to-peer computer process used to secure and verify bitcoin transactions—payments from one user to another on a decentralized network. Mining involves adding bitcoin transaction data to Bitcoin’s global public ledger of past transactions. Each group of transactions is called a block.

Blocks are secured by Bitcoin miners and build on top of each other forming a chain. This ledger of past transactions is called the blockchain. The blockchain serves to confirm transactions to the rest of the network as having taken place.

Bitcoin nodes use the blockchain to distinguish legitimate Bitcoin transactions from attempts to re-spend coins that have already been spent elsewhere.

What is Proof-of-Work?

Bitcoin Mining is intentionally designed to be resource-intensive and difficult so that the number of blocks found each day by miners remains steady over time, producing a controlled finite monetary supply. Individual blocks must contain a proof-of-work to be considered valid. This proof-of-work (PoW) is verified by other Bitcoin nodes each time they receive a block. Bitcoin uses a PoW function to protect against double-spending, which also makes Bitcoin’s ledger immutable.

What is Bitcoin Mining Actually Doing?

What is the point of Bitcoin mining? This is something we’re asked everyday!

There are many aspects and functions of Bitcoin mining and we’ll go over them here. They are:

• Issuance of new bitcoins
• Confirming transactions
• Security

Mining Is Used to Issue new Bitcoins

Traditional currencies–like the dollar or euro–are issued by central banks. The central bank can issue new units of money ay anytime based on what they think will improve the economy.

Bitcoin is different.

With Bitcoin, miners are rewarded new bitcoins every 10 minutes.

The issuance rate is set in the code, so miners cannot cheat the system or create bitcoins out of thin air. They have to use their computing power to generate the new bitcoins.

How Does Mining Create New Bitcoins?

The primary purpose of mining is to allow Bitcoin nodes to reach a secure, tamper-resistant consensus. Mining is also the mechanism used to introduce bitcoins into the system. Miners are paid transaction fees as well as a subsidy of newly created coins, called block rewards. This both serves the purpose of disseminating new coins in a decentralized manner as well as motivating people to provide security for the system through mining.

What Are Bitcoin Mining Pools?

During the last several years an incredible amount of Bitcoin mining power (hashrate) has come online making it harder for individuals to have enough hashrate to single-handedly solve a block and earn the payout reward. To compensate for this pool mining was introduced. Pooled mining is a mining approach where groups of individual miners contribute to the generation of a block, and then split the block reward according the contributed processing power.

Introducing the Bitcoin.com Mining Pool

Bitcoin.com has developed its own modern Bitcoin mining pool which offers two different payout methods, Pay Per Share (PPS) and Pay Per Last N Shares (PPLNS). Start mining on pool.bitcoin.com today to take advantage of our competitive cloud mining contracts.

Miners Confirm Transactions

Miners include transactions sent on the Bitcoin network in their blocks.

A transaction can only be considered secure and complete once it is included in a block.

Why?

Because only a when a transaction has been included in a block is it officially embedded into Bitcoin’s blockchain.

More confirmations are better for larger payments. Here is a visual so you have a better idea:

1. Payments with 0 confirmations can still be reversed! Wait for at least one.
2. One confirmation is enough for small Bitcoin payments less than $1,000.
3. Enough for payments $1,000 – $10,000. Most exchanges require 3 confirmations for deposits.
4. Enough for large payments between $10,000 – $1,000,000. Six is standard for most transactions to be considered secure.

How Does Bitcoin Mining Work?

This simplified illustration is helpful to explanation:

1) Spending

Let’s say the Green user wants to buy some goods from the Red user. Green sends 1 bitcoin to Red.

2) Announcement

Green’s wallet announces a 1 bitcoin payment to Red’s wallet. This information, known as transaction (and sometimes abbreviated as “ tx”) is broadcast to as many Full Nodes as connect with Green’s wallet – typically 8. A full node is a special, transaction-relaying wallet which maintains a current copy of the entire blockchain.

3) Propagation

Full Nodes then check Green’s spend against other pending transactions. If there are no conflicts (e.g. Green didn’t try to cheat by sending the exact same coins to Red and a third user), full nodes broadcast the transaction across the Bitcoin network. At this point, the transaction has not yet entered the Blockchain. Red would be taking a big risk by sending any goods to Green before the transaction is confirmed. So how do transactions get confirmed? This is where Miners enter the picture.

4) Processing by Miners

Miners, like full nodes, maintain a complete copy of the blockchain and monitor the network for newly-announced transactions. Green’s transaction may in fact reach a miner directly, without being relayed through a full node. In either case, a miner then performs work in an attempt to fit all new, valid transactions into the current block.

Miners race each other to complete the work, which is to “package” the current block so that it’s acceptable to the rest of the network. Acceptable blocks include a solution to a Proof of Work computational problem, known as ahash . The more computing power a miner controls, the higher their hashrate and the greater their odds of solving the current block.

But why do miners invest in expensive computing hardware and race each other to solve blocks? Because, as a reward for verifying and recording everyone’s transactions, miners receive a substantial Bitcoin reward for every solved block!

And what is a hash? Well, try entering all the characters in the above paragraph, from “But” to “block!” into this hashing utility. If you pasted correctly – as a string hash with no spaces after the exclamation mark – the SHA-256 algorithm used in Bitcoin should produce:

“6afc21238f2d33e24e168195888721dd5ace05d76196671d6739789af92201ed.”

If the characters are altered even slightly, the result won’t match. So, a hash is a way to verify any amount of data is accurate. To solve a block, miners modify non-transaction data in the current block such that their hash result begins with a certain number (according to the current Difficulty, covered below) of zeroes. If you manually modify the string until you get a 0… result, you’ll soon see why this is considered “Proof of Work!”

5) Blockchain Confirmation

The first miner to solve the block containing Green’s payment to Red announces the newly-solved block to the network. If other full nodes agree the block is valid, the new block is added to the blockchain and the entire process begins afresh. Once recorded in the blockchain, Green’s payment goes from pending to confirmed status.

Red may now consider sending the goods to Green. However, the more new blocks are layered atop the one containing Green’s payment, the harder to reverse that transaction becomes. For significant sums of money, it’s recommended to wait for at least 6 confirmations. Given new blocks are produced on average every ten minutes; the wait shouldn’t take much longer than an hour.

The Longest Valid Chain

You may have heard that Bitcoin transactions are irreversible, so why is it advised to await several confirmations? The answer is somewhat complex and requires a solid understanding of the above mining process:

Let’s imagine two miners, A in China and B in Iceland, who solve the current block at roughly the same time. A’s block (A1) propagates through the internet from Beijing, reaching nodes in the East. B’s block (B1) is first to reach nodes in the West. There are now two competing versions of the blockchain!

Which blockchain prevails? Quite simply, the longest valid chain becomes the official version of events. So, let’s say the next miner to solve a block adds it to B’s chain, creating B2. If B2 propagates across the entire network before A2 is found, then B’s chain is the clear winner. A loses his mining reward and fees, which only exist on the invalidated A -chain.

Going back to the example of Green’s payment to Red, let’s say this transaction was included by A but rejected by B, who demands a higher fee than was included by Green. If B’s chain wins then Green’s transaction won’t appear in the B chain – it will be as if the funds never left Green’s wallet.

Although such blockchain splits are rare, they’re a credible risk. The more confirmations have passed, the safer a transaction is considered.