What is Bitcoin
The Bitcoin Network
Bitcoin’s payment network (also called the bitcoin blockchain) is what makes it possible for us to transact with one another. The network uses distributed consensus to verify and confirm transactions, and consensus is reached via a large global network of high-performance computers (called miners) running the bitcoin software.
Whenever someone sends a transaction it is broadcast instantly to the network and verified by the miners. Miners are constantly working to confirm individual transactions and include them in the next block of transactions in the chain. Once a new block is verified, all the transactions within it are permanently recorded on the blockchain. Rewards are paid out in bitcoin to miners who confirm transactions and verify the next block as a way to incentivize productivity on the network.
Each party who participates in the mining process has an identical up-to-date copy of the blockchain or public ledger, which is a record of all the transactions in bitcoin history. Each party’s copy of the ledger is updated every time a new block is found.
What Is Cryptocurrency?
A cryptocurrency is a medium of exchange like normal currencies such as USD, but designed for the purpose of exchanging digital information through a process made possible by certain principles of cryptography. Cryptography is used to secure the transactions and to control the creation of new coins.
The unit of value that we send and receive on the Bitcoin network is also referred to as bitcoin, or bitcoins. Bitcoin is completely digital, meaning we can’t physically hold it in our hand. It’s also portable, divisible, fungible, and irreversible.
Bitcoin (the protocol and payment network)
Bitcoin with a capital “B” is typically associated with Bitcoin the protocol and payment network. The uppercase form, “Bitcoin,” is also often used to refer to as the ecosystem as a whole. Using Bitcoin with a capital “B” is the common way of referencing Bitcoin when writing about it in general terms.
An example would be, “I just learned about Bitcoin, and it’s a fast and cheap way for merchants to accept payments.”
Bitcoin (the currency)
Bitcoin with a lowercase “b” written as “bitcoin” is usually associated specifically with bitcoin as the currency. When you intend to reference how much of the currency was transacted, or you’re focusing solely on the currency and not the broader payment network or protocol as a whole, you can use the lowercase form, “bitcoin.”
An example would be, “I just sent two bitcoins from my Blockchain Wallet to the merchant.”
What is Blockchain Technology?
The term “blockchain technology” typically refers to the transparent, trustless, publicly accessible ledger that allows us to securely transfer the ownership of units of value using public key encryption and proof of work methods.
The technology uses decentralized consensus to maintain the network, which means it is not centrally controlled by a bank, corporation, or government. In fact, the larger the network grows and becomes increasingly decentralized, the more secure it becomes.
The potential for blockchain technology is not limited to bitcoin. As such, it has gained a lot of attention in a variety of industries including: financial services, charities and nonprofits, the arts, and e-commerce.
Can my Transaction be Canceled or Reversed?
Even many advanced bitcoin users can recall an incident when they failed to double-check their transaction details and they accidentally sent bitcoin to the wrong recipient, or sent the wrong amount. As unfortunate as it is, transactions on the Bitcoin network are designed to be irreversible and we have no control over them.
Knowing this, it’s extremely important to make sure your transaction details are correct before you click send.
To learn more about why bitcoin transactions can’t be canceled and how this aspect of bitcoin compares to other methods of payment like credit cards and cash, check out our blog post on Bitcoin Transactions & Chargebacks.
How Bitcoin Mining Works
In traditional fiat money systems, governments simply print more money when they need to. But in bitcoin, money isn’t printed at all – it is discovered. Computers around the world ‘mine’ for coins by competing with each other.
How does mining take place?
People are sending bitcoins to each other over the bitcoin network all the time, but unless someone keeps a record of all these transactions, no-one would be able to keep track of who had paid what. The bitcoin network deals with this by collecting all of the transactions made during a set period into a list, called a block. It’s the miners’ job to confirm those transactions, and write them into a general ledger.
Making a hash of it
This general ledger is a long list of blocks, known as the ‘blockchain’. It can be used to explore any transaction made between any bitcoin addresses, at any point on the network. Whenever a new block of transactions is created, it is added to the blockchain, creating an increasingly lengthy list of all the transactions that ever took place on the bitcoin network. A constantly updated copy of the block is given to everyone who participates, so that they know what is going on.
But a general ledger has to be trusted, and all of this is held digitally. How can we be sure that the blockchain stays intact, and is never tampered with? This is where the miners come in.
When a block of transactions is created, miners put it through a process. They take the information in the block, and apply a mathematical formula to it, turning it into something else. That something else is a far shorter, seemingly random sequence of letters and numbers known as a hash. This hash is stored along with the block, at the end of the blockchain at that point in time.
Hashes have some interesting properties. It’s easy to produce a hash from a collection of data like a bitcoin block, but it’s practically impossible to work out what the data was just by looking at the hash. And while it is very easy to produce a hash from a large amount of data, each hash is unique. If you change just one character in a bitcoin block, its hash will change completely.
Miners don’t just use the transactions in a block to generate a hash. Some other pieces of data are used too. One of these pieces of data is the hash of the last block stored in the blockchain.
Because each block’s hash is produced using the hash of the block before it, it becomes a digital version of a wax seal. It confirms that this block – and every block after it – is legitimate, because if you tampered with it, everyone would know.
If you tried to fake a transaction by changing a block that had already been stored in the blockchain, that block’s hash would change. If someone checked the block’s authenticity by running the hashing function on it, they’d find that the hash was different from the one already stored along with that block in the blockchain. The block would be instantly spotted as a fake.
Because each block’s hash is used to help produce the hash of the next block in the chain, tampering with a block would also make the subsequent block’s hash wrong too. That would continue all the way down the chain, throwing everything out of whack.
Competing for coins
So, that’s how miners ‘seal off’ a block. They all compete with each other to do this, using software written specifically to mine blocks. Every time someone successfully creates a hash, they get a reward of 25 bitcoins, the blockchain is updated, and everyone on the network hears about it. That’s the incentive to keep mining, and keep the transactions working.
The problem is that it’s very easy to produce a hash from a collection of data. Computers are really good at this. The bitcoin network has to make it more difficult, otherwise everyone would be hashing hundreds of transaction blocks each second, and all of the bitcoins would be mined in minutes. The bitcoin protocol deliberately makes it more difficult, by introducing something called ‘proof of work’.
Bitcoin protocol won’t just accept any old hash. It demands that a block’s hash has to look a certain way; it must have a certain number of zeroes at the start. There’s no way of telling what a hash is going to look like before you produce it, and as soon as you include a new piece of data in the mix, the hash will be totally different.
Miners aren’t supposed to meddle with the transaction data in a block, but they must change the data they’re using to create a different hash. They do this using another, random piece of data called a ‘nonce’. This is used with the transaction data to create a hash. If the hash doesn’t fit the required format, the nonce is changed, and the whole thing is hashed again. It can take many attempts to find a nonce that works, and all the miners in the network are trying to do it at the same time. That’s how miners earn their bitcoins. You can learn how to trade cryptocurrency here.