Complex sentence: Ransomware is a type of malware that can be covertly installed on a computer without knowledge or intention of the user that restricts access to the infected computer system in some way, and demands that the user pay a ransom to the malware operators to remove the restriction.
Split into simpler sentences: Ransomware is a type of malware that can be covertly installed on a computer without knowledge or intention of the user. It can restricts access to the infected computer system in some way, and demands that the user pay a ransom to the malware operators to remove the restriction.