Ransomware is a type of malicious software, also known as malware. It encrypts a victim’s data until the attacker is paid a predetermined ransom. Typically, the attacker demands payment in a form of cryptocurrency such as bitcoin. Only then will the attacker send a decryption key to release the victim’s data. A number of ransomware variants have appeared in recent years, which we’ll describe in greater detail below. We will also explain how you can protect your system against future attacks.