Cyber terrorism is the use of Internet to perform violent threatening actions in order to achieve political gains. These terrorist activities may include the disruption of computer networks by using computer viruses, computer worms , phishing, and other cruel software and hardware methods. Many of these cyber terrorist attacks cause massive damage to government systems, hospital records, and national security programs. As a results these terrorised countries,organizations, or communities will face disturbance due to the constant fear. Many of these terrorists attack due to these possible motives:1- they’re trying to terrify a government or a section of the public to varying degrees2- These actions are guided by a certain political, religious, or ideological cause Spanish protesters bombarded the Institute for Global Communications (IGC) with thousands of bogus email messages. They stopped any communication between the ISP and the IGC. The protesters used the staffs’ credit cards to purchase items online, they spammed the institution and members accounts, and they threatened to do the same to organizations using IGC service. Protesters said IGC supported terrorism because a section on the Web pages contained materials on the terrorist group ETA, which claimed responsibility for assassinations of Spanish political and security officials, and attacks on military installations. IGC finally pulled the site because of the “mail bombings.”1998Tamil Guerrillas attempted to disrupt Sri Lankan embassies by sending large volumes of email. The embassies received 800 e-mails a day over a two-week period. The messages read “We are the Internet Black Tigers and we’re doing this to disrupt your communications.” 1999NATO computers were spammed with e-mail bombs and hit with denial-of-service attacks by hacktivists protesting the NATO bombings. In addition, businesses, public organizations, and academic institutes received highly politicized virus-laden emails from Eastern European countries.Web defacements were also common. After the Chinese Embassy was unintentionally bombed in Belgrade,Chinese hacktivists posted the following message “We won’t stop attacking until the war stops!” on U.S. government Web sites.1997Since December of 1997, the Electronic Disturbance Theater (EDT) has holding been holding web siti-ins against websites in support of Mexican Zapatistas. Thousand of protesters spammed sites by using a software that sends the target repeated and non stopping download requests. EDT software was also used by an animal rights group against organizations that abused animals. 2000 Japanese Investigations revealed that the government was using software developed by computer companies affiliated with Aum Shinrikyo, the doomsday sect responsible for the sarin gas attack on the Tokyo subway system in 1995.After the investigation, the Japanese government suspended use of Aum-developed programs out of concern that Aum-related companies might tear down their firewalls.March 2013 The New York Times reported a pattern of cyber attacks against U.S. financial institutions.it was believed to be brought by Iran. The same type of incident occurred to the South Korean financial institutions that originate with the North Korean government.August 2013 Media companies like the New York Times, Twitter and the Huffington Post lost control of some of their websites after hackers supporting the Syrian government breached the Australian Internet company that manages many major site addresses. The Syrian Electronic Army, a hacker group that has previously attacked media organisations who are hostile to the regime of Syrian president Bashar al-Assad, admitted for the Twitter and Huffington Post hacks in a series of Twitter messages. Electronic records showed that NYTimes.com redirected visitors to a server controlled by the Syrian group before it went dark.Currently active Pakistani Cyber Army(PCA) is the name taken by a group of hackers who are known for attacking websites including Indian,Chinese, and Israeli companies and governmental organizations, claiming to represent Pakistani nationalist and Islamic interests.This group started and 2008 and still remains active on social media, specifically Facebook. PCA was responsible of the cyber attacks against websites belonging to Acer, BSNL, Indians CBI, Central Bank, and the state government of Kerala.Main Occurrences of cyberterrorism: Estonia: A series of cyber attacks began 27 April 2007 that overloaded websites of Estonian organizations, including Estonian parliament, banks, ministries, newspapers and broadcasters, amid the country’s disagreement with Russia about the relocation of the Bronze Soldier of Tallinn, The severity of the Estonian cyber attacks served as a wake-up call to the world, as it became clear that potentially autonomous transnational networks like unhappy hackers could avenge their grievances by digitally targeting and nearly crippling the critical infrastructure of technically sophisticated nation states. South Korea:In April 2011,a virus attacked 10 servers of South Korea’s agricultural companies known as Nonghyup, affecting 30 million users. They could not use ATMs and online services. On July 4, 2009 another malicious software virus attacked South Korea government websites through a “denial of service” scheme. Furthermore, the attack affected several U.S. government websites as well . South Korean authorities believe North Korea is responsible for these cyber attacks. But they do not have evidence to support their claim.Ukraine :Ukrainian banks and companies, including the state power distributor, have been hit by a cyber attack on the government’s infrastructure.The latest disruptions follow a spate of hacking attempts on state websites in late-2016 and repeated attacks on Ukraine’s power grid that prompted security chiefs to call for improved cyber defences. China : In 2013, it was revealed that the United States government had hacked into Chinese mobile phone companies to collect text messages and had spied on Tsinghua University, which is China’s biggest research institution it is also one of China’s six major backbone networks, the China Education and Research Network (CERNET), from where internet data from millions of Chinese citizens could be mined. This lead to a cyber warfare between the US and China. Pakistan :The Pakistan government has taken steps to abolish cyberterrorism, The National Counter Terrorism Authority (NACTA) is working with cyber security organizations in Pakistan in order to resolve this issue. Surf Safe Pakistan is a website where people can report any extremist and terrorist related content found on the Internet.