There are many ways to earn Bitcoin, all have their pros and cons, also depending on the risk-reward ratio. One would be mining. Bitcoin mining is the process through which Bitcoins are released to come into circulation. In simple words it involves solving a computationally difficult puzzle to discover a new block which is added to the blockchain and receiving a reward in the form of few Bitcoins. Another method is to join signature campaigns, why is a relatively risk-free way to earn Bitcoins by providing your service. One more method would be to participate in trading, which would entail strategic thinking and investing in the market with a volatile risk-reward ratio.