Bitcoin is transferable peer-to-peer across a network that extends to every corner of the world. Functionally, sending bitcoin across continents is as easy as sending an email. In the same way that emails are sent from applications called mailboxes, bitcoins are sent from applications called wallets. Wallets are freely available to anyone, and exist independently – i.e., without reliance on, or assistance from, any third party such as a bank, financial institution or government.
The initial phases of a transfer – creating and signing a transaction – are completed by the user through stored cryptographic keys within their wallet. The next step in the transfer process – broadcasting a transaction – is most commonly achieved over the Internet. However, technically transactions can be broadcast over any communications channel so long as it can be reliably delivered to the recipient on the other end. For example, radio, satellite and cell phone networks have all proven to be viable methods of communicating transactions outside of the Internet. So long as a transaction doesn’t break any Bitcoin rules, it is relayed through the network by full nodes, eventually being processed by a miner into a block, which is then verified by the rest of the network.