Ransomware is a type of malware that attempts to extort money from a computer user by infecting and taking control of the victim's machine, or the files or documents stored on it. Typically, the ransomware will either 'lock' the computer to prevent normal usage, or encrypt the documents and files on it to prevent access to the saved data. The first known ransomware was the 1989 "AIDS" Trojan, also known as "PC Cyborg" written by Joseph Popp. Also, extortionate ransomware became prominent in May 2005. Ransomware generates a pop-up window, webpage, or email warning from what looks like an official authority. In addition, “Ransomware” is usually installed when you open the following: A malicious email attachment, clicking a malicious link in an email message or an instant message on social networking site. Moreover, “Ransomware” can even be installed when you visit a malicious website. Overall, there are three main types of Ransomware such as: Encryption Ransomware and CryptoLocker, Lock Screen Ransomware, and Master Boot Record (MBR) Ransomware. Finally, when it comes to malware attacks, knowledge is the best possible weapon to prevent them. Be careful what you click!! Preventive measures should be taken before ransomwares establish strong hold. Keeping all the software updated and getting latest security updates might help to prevent the attacks. Use of antivirus and original software is highly recommended. Creating software restriction policy is the best tool to prevent a Cryptolocker infection in the first place in networks .