How does Bitcoin work?
This is a question that often causes confusion. Here's a quick explanation!
The basics for a new user
As a new user, you can get started with Bitcoin without understanding the technical details. Once you have installed a Bitcoin wallet on your computer or mobile phone, it will generate your first Bitcoin address and you can create more whenever you need one. You can disclose your addresses to your friends so that they can pay you or vice versa. In fact, this is pretty similar to how email works, except that Bitcoin addresses should only be used once.
Bitcoin
Balances - block chain
The block chain is a shared public ledger on which the entire Bitcoin network relies. All confirmed transactions are included in the block chain. This way, Bitcoin wallets can calculate their spendable balance and new transactions can be verified to be spending bitcoins that are actually owned by the spender. The integrity and the chronological order of the block chain are enforced with cryptography.
Transactions - private keys
A transaction is a transfer of value between Bitcoin wallets that gets included in the block chain. Bitcoin wallets keep a secret piece of data called a private key or seed, which is used to sign transactions, providing a mathematical proof that they have come from the owner of the wallet. The signature also prevents the transaction from being altered by anybody once it has been issued. All transactions are broadcast between users and usually begin to be confirmed by the network in the following 10 minutes, through a process called mining.
Processing - mining
Mining is a distributed consensus system that is used to confirm waiting transactions by including them in the block chain. It enforces a chronological order in the block chain, protects the neutrality of the network, and allows different computers to agree on the state of the system. To be confirmed, transactions must be packed in a block that fits very strict cryptographic rules that will be verified by the network. These rules prevent previous blocks from being modified because doing so would invalidate all following blocks. Mining also creates the equivalent of a competitive lottery that prevents any individual from easily adding new blocks consecutively in the block chain. This way, no individuals can control what is included in the block chain or replace parts of the block chain to roll back their own spends.
Going down the rabbit hole
This is only a very short and concise summary of the system. If you want to get into the details, you can read the original paper that describes the system's design, read the developer documentation, and explore the Bitcoin wiki.
Bitcoin Price
Like everything, Bitcoin’s price is determined by the laws of supply and demand. Because the supply is limited to 21 million bitcoins, as more people use Bitcoin the increased demand, combined with the fixed supply, will force the price to go up. Because the number of people using Bitcoin in the world is still relatively small, the price of Bitcoin in terms of traditional currency can fluctuate significantly on a daily basis, but will continue to increase as more people start to use it. For example, in early 2011 one Bitcoin was worth less than one USD, but in 2015 one Bitcoin is worth hundreds of USD. In the future, if Bitcoin becomes truly popular, each single Bitcoin will have to be worth at least hundreds of thousands of dollars in order to accommodate this additional demand.
Bitcoin Exchanges
There are several ways to buy Bitcoin, but trusted exchanges are a great way to acquire Bitcoin. Because there are inefficiencies in the traditional banking system, exchanges will sometimes have slightly different prices. If the difference is too great, traders will buy low on one an exchange and sell high on another and close the gap. If an exchange constantly has substantially different prices than others, it is a sign of trouble and that exchange should be avoided. As with everything else, do your research and find an exchange you can trust. It’s also a good idea not to use an exchange as a wallet. Move your Bitcoin to your personal wallet so that you have control over your funds at all times.