Cyberterrorism is the use of the Internet to conduct violent acts that result in, or threaten, the loss of life or significant bodily harm, in order to achieve political or ideological gains through threat or intimidation. Emerging alongside the development of information technology, cyberterrorism involves acts of deliberate, large-scale disruption of computer networks, especially of personal computers attached to the Internet by means of tools such as computer viruses, computer worms, phishing, malicious software, hardware methods, and programming scripts can all be forms of internet terrorism. Some authors opt for a very narrow definition of cyberterrorism, relating to deployment by known terrorist organizations of disruption attacks against information systems for the primary purpose of creating alarm, panic, or physical disruption. Other authors prefer a broader definition, which includes cybercrime. Participating in a cyberattack affects the terror threat perception, even if it isn't done with a violent approach. By some definitions, it might be difficult to distinguish which instances of online activities are cyberterrorism or cybercrime.

Cyberterrorism can be also defined as the intentional use of computers, networks, and public internet to cause destruction and harm for personal objectives. Experienced cyberterrorists, who are very skilled in terms of hacking can cause massive damage to government systems and might leave a country in fear of further attacks. The objectives of such terrorists may be political or ideological since this can be considered a form of terror.

There is much concern from government and media sources about potential damage that could be caused by cyberterrorism, and this has prompted efforts by government agencies such as the Federal Bureau of Investigation (FBI), National Security Agency (NSA), and the Central Intelligence Agency (CIA) to put an end to cyber attacks and cyberterrorism.

There have been several major and minor instances of cyberterrorism. Al-Qaeda utilized the internet to communicate with supporters and even to recruit new members. Estonia, a Baltic country which is constantly evolving in terms of technology, became a battleground for cyberterrorism in April 2007 after disputes regarding the relocation of a WWII soviet statue located in Estonia's capital Tallinn.

There is debate over the basic definition of the scope of cyberterrorism. These definitions can be narrow such as the use of Internet to attack other systems in the Internet that result to violence against persons or property. They can also be broad, those that include any form of Internet usage by terrorists to conventional attacks on information technology infrastructures. There is variation in qualification by motivation, targets, methods, and centrality of computer use in the act. U.S. government agencies also use varying definitions and that none of these have so far attempted to introduce a standard that is binding outside of their sphere of influence.

Depending on context, cyberterrorism may overlap considerably with cybercrime, cyberwar or ordinary terrorism. Eugene Kaspersky, founder of Kaspersky Lab, now feels that "cyberterrorism" is a more accurate term than "cyberwar". He states that "with today's attacks, you are clueless about who did it or when they will strike again. It's not cyber-war, but cyberterrorism." He also equates large-scale cyber weapons, such as the Flame Virus and NetTraveler Virus which his company discovered, to biological weapons, claiming that in an interconnected world, they have the potential to be equally destructive.

If cyberterrorism is treated similarly to traditional terrorism, then it only includes attacks that threaten property or lives, and can be defined as the leveraging of a target's computers and information, particularly via the Internet, to cause physical, real-world harm or severe disruption of infrastructure.

Many academics and researchers who specialize in terrorism studies suggest that cyberterrorism does not exist and is really a matter of hacking or information warfare. They disagree with labeling it as terrorism because of the unlikelihood of the creation of fear, significant physical harm, or death in a population using electronic means, considering current attack and protective technologies.