Cyber extortion involves attacking or threatening to attack a target and demanding money to stop the attack. Originally, denial of service attacks against websites were common, but now ransomware that encrypts victims' data and demands payment in bitcoin in exchange for the decryption key is prevalent. Cyber extortion can earn attackers millions annually. Most efforts start through malware in emails or websites, so users should be educated on phishing and back up devices regularly to mitigate risks.