What type of malware locks a user's files until a ransom is paid?

Ransomware is a type of malware designed specifically to restrict access to a user's files, often by encrypting them, until a ransom is paid to the attacker. This method puts immense pressure on the victim, who may be forced to consider paying the ransom to regain access to their essential data. Ransomware attacks typically involve a demand for payment, which can be made through cryptocurrencies to ensure anonymity for the attackers.

Adware primarily serves as a tool that displays advertisements and collects user data for marketing purposes, without necessarily locking or encrypting files. Spyware is used to gather personal information from the user's device silently, often used for identity theft but does not typically involve access restrictions or ransom. A Trojan, on the other hand, disguises itself as legitimate software to gain access to a system but can facilitate other types of malicious activity, including the installation of ransomware, without having the file-locking mechanism itself. Thus, ransomware is distinct in its main feature of locking files and requiring payment for access restoration.