Cybercrime encompasses a wide range of criminal activities that are carried out using digital devices and/or networks. These crimes involve the use of technology to commit fraud, identity theft, data breaches, computer viruses, scams, and expanded upon in other malicious acts. Internationally, both state and non-state actors engage in cybercrimes, including espionage, financial theft, and other cross-border crimes. Cybercrimes crossing international borders and involving the actions of at least one nation-state are sometimes referred to as cyberwarfare. Warren Buffett has described that cybercrime is the "number one problem with mankind" and that it "poses real risks to humanity". Computer fraud is the act of using a computer to take or alter electronic data, or to gain unlawful use of a computer or system. Computer fraud that involves the use of the internet is also called internet fraud. The legal definition of computer fraud varies by jurisdiction, but typically involves accessing a computer without permission or authorization. The term cyberterrorism refers to acts of terrorism committed through the use of cyberspace or computer resources. Acts of disruption of computer networks and personal computers through viruses, worms, phishing, malicious software, hardware, or programming scripts can all be forms of cyber terrorism. Cyberextortion occurs when a website, e-mail server, or computer system is subjected to or threatened with attacks by malicious hackers, often through denial-of-service attacks. Cyber extortionists demand money in return for promising to stop the attacks and provide "protection". Ransomware is a type of malware used in cyberextortion to restrict access to files, sometimes threatening permanent data erasure unless a ransom is paid. Ransomware is a global issue, with more than 300 million attacks worldwide in 2021. Cybersex trafficking is the transportation of victims for such purposes as coerced prostitution or the live streaming of coerced sexual acts or rape on webcam.