Ransomware:
Ransomware is a form of malware that locks you out of your device and/or encrypts your files, then forces you to pay a ransom to get them back. Ransomware has been called the cybercriminal's weapon of choice, because it demands a profitable quick payment in hard-to-trace cryptocurrency.
The cybercriminals behind the GandCrab ransomware claimed to have brought in over $2 billion in ransom payments over the course of a year and a half.