The birth of computer criminality began with hackers who gravitated toward phone phreaking in the 1960s and 1970s. Cybercrime refers to "the use of computers or other electronic devices via information systems such as organizational networks or the Internet to facilitate illegal behaviors". One of the most cited examinations of organized cybercrime reviewed a large number of cybercrime investigations and found that close to 80 percent of them were "the result of some form of organized activity". Despite the demise of Silk Road, dozens of "dark-net Amazons and eBays have sprung up to fill the void". Malware or malicious viruses are specifically created to alter or erase data, crash the host system, and other related motivations. Cyber blackmail is increasing, particularly as a strategy focusing on specific computer users and then sending them e-mails that threaten to delete essential files or install pornographic images on their work computers unless they pay a ransom.