The block chain is a shared public ledger on which the entire Bitcoin network relies. All confirmed transactions are included in the block chain. It allows Bitcoin wallets to calculate their spendable balance so that new transactions can be verified thereby ensuring they're actually owned by the spender. The integrity and the chronological order of the block chain are enforced with cryptography.
Mining is a distributed consensus system that is used to confirm pending 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 the subsequent blocks.
When you trade forex with a spread betting or CFD provider you are not actually exchanging any currency.
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 to the network and usually begin to be confirmed within 10-20 minutes, through a process called mining.
Trading Forex, also known as foreign exchange, FX or currency trading, is a decentralized global market where all the world's currencies trade. The forex market is the largest, most liquid market in the world with an average daily trading volume exceeding $5 trillion.