Ransomware
In plain terms
Malware that encrypts data and demands payment to release it.
Going deeper
Ransomware locks victims out of their files via encryption and demands a ransom for the decryption key. It can cripple organizations.
Under the hood
Often paired with data exfiltration ('double extortion'); backups and segmentation are key defenses.
Examples
WannaCry, encrypted-file attacks, extortion, backup-based recovery.
Think of it like...
Like a thief changing all your locks and demanding money for the new keys.