The most common way to buy Bitcoin is through online services such as Coinbase, Bitpanda, Bitquick, Localbitcoins, and Spectrocoin, where customers can use credit cards, bank accounts, and various other payment methods to convert cash into coin.
Transfers are based on frequently updated rates of exchange and may involve a combination of flat fees and percentages that go to the service. There are also some physical locations where you can perform these transactions, such as Bitcoin ATM machines and convenience stores that can help you transfer money through the same machines that add funds to prepaid phones. Each of these methods offers different advantages in terms of convenience, anonymity, and security.
Many people also use bitcoin as an investment rather than as a currency. For these people, investment options such as ETFs and hedge funds which hold large positions in bitcoin are available. People can also buy interest shares in a bitcoin mining pool and acquire the cryptocurrency through the dividends from the mining collective.
Be aware that Coinbase and other exchanges may not be the ideal place to store your bitcoins once you have acquired them. Some of these services offer to hold your bitcoin on deposit, in possession of your personal key that can unlock your funds, much like a bank.
Allowing your key to exist in a database with other keys invites security attacks and breaches, and billions of dollars worth of bitcoin have been lost in this way. Many exchanges exist on the web where bitcoin and other cryptocurrencies are traded all over the world in a manner very similar to the mainstream Forex currency markets. These platforms include Kraken, Bitfinex, ViaBTC, and many others.