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. 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, programming scripts can all be forms of internet terrorism. Cyberterrorism is a controversial term. Some authors opt for a very narrow definition, 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) 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.