Ransomware is a form of malware that encrypts your sensitive data, meaning you cannot access your computer or the data. The hackers demand a ransom in Bitcoin in exchange for the decryption keys. WannaCry exploited a vulnerability in the Windows OS that might have been a hack discovered by the NSA. The NSA did not report the vulnerability when they discovered it and decided to develop a code known as EternalBlue to exploit the vulnerability. Microsoft had discovered the said vulnerability a month before and released a security patch but most people had not updated their systems.”]