Ransomware is a kind of malware (malicious software) criminals install on your computer so they can lock it from a remote location. Ransomware generates a pop-up window, webpage, or email warning from what looks like an official authority. It explains that your computer has been locked because of possible illegal activities on it and demands payment before you can access your files and programs again.
It is recommended you do not pay the ransom. There is no guarantee your information will be unlocked, nor that the criminals will not just lock your information up again in the future knowing you will pay.