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Bitcoin is now over 11 years old, with 18.206 million BTC generated on the network. The supply of these currencies is often generated through a process called "mining" This process is completed by solving complex mathematics on the Bitcoin network. Every 210,000 blocks, the reward associated with solving the block's mathematics is cut in half. The fixed supply of Bitcoin has been decided upon by the creator, Satoshi Nakamoto. In total, there will never be more than 21 million BTC in circulation. The halvings occur automatically from Bitcoin's inception.