What type of malware encrypts files and demands payment to restore access?

Ransomware is a specific type of malware designed to block access to a computer system or file until a sum of money is paid. It typically encrypts the files on the infected system, making them inaccessible to the user. Once the files are encrypted, the attackers demand payment, usually in cryptocurrency, to provide the decryption key that will restore access. This financial motivation is a key distinguishing factor of ransomware compared to other types of malware, which might focus on gathering information, delivering unwanted advertisements, or gaining unauthorized access to systems without monetary demands.