Terrorism is a complex issue that involves a variety of factors, such as political, religious, ideological, and socioeconomic factors. The root causes of terrorism can vary depending on the context, history, and culture of each region. However, some common themes and patterns can be observed across different terrorist groups and attacks.

One common factor that often leads to terrorism is political grievances. Many terrorist groups emerge as a response to perceived injustices or oppression by a government or ruling authority. For example, the Irish Republican Army (IRA) in Ireland and the Basque separatist group ETA in Spain were formed as a result of their communities' perceived marginalization and mistreatment by the ruling authorities. In other cases, terrorist groups aim to overthrow a government or establish a new political system. For example, the Maoist insurgency in Nepal aimed to replace the country's monarchy with a communist system.

Religious extremism is another factor that can lead to terrorism. Some religious groups believe that their faith is under threat by other religions or secularism, and they resort to violence to protect their beliefs. For example, Al-Qaeda and ISIS are both Sunni Islamic extremist groups that use violence to promote their interpretation of Islam and attack perceived enemies of the faith. In other cases, religious differences between communities can lead to terrorist attacks. For example, the conflict between Hindus and Muslims in India has led to several terrorist attacks targeting each other's communities.

Ideological extremism is another factor that can lead to terrorism. Some extremist groups hold extreme political or social ideologies that they believe are under threat by the mainstream society or government. For example, far-right groups in Europe and North America often hold anti-immigrant, anti-Semitic, or white supremacist views and use violence to promote their ideology. Left-wing extremist groups, such as the Red Brigades in Italy and the Weather Underground in the United States, also use violence to promote their revolutionary socialist or anarchist ideologies.

Socioeconomic factors can also contribute to the emergence of terrorist groups. Poverty, unemployment, and inequality can create a sense of hopelessness and frustration among marginalized communities, which can be exploited by extremist groups. In some cases, terrorist groups offer economic opportunities, protection, or social services to communities that are neglected by the government. For example, Hezbollah in Lebanon provides social and economic services to the Shiite Muslim community, which has been historically marginalized by the country's ruling class.

The use of terrorism as a tactic can also be influenced by external factors, such as foreign intervention, regional conflicts, or globalization. For example, the rise of Al-Qaeda and ISIS can be partly attributed to the US-led wars in Afghanistan and Iraq, which created a power vacuum and provided a breeding ground for extremist groups. The conflict between Israel and Palestine has also led to several terrorist attacks by Palestinian groups targeting Israeli civilians. The rise of globalization has also enabled terrorist groups to coordinate their activities and spread their ideology through the internet and social media.

In conclusion, the background of terrorist attacks in the world is complex and multifaceted. While each terrorist group and attack has its unique context and motivations, political grievances, religious extremism, ideological extremism, socioeconomic factors, and external factors can all play a role in the emergence of terrorist groups and the use of terrorism as a tactic. Understanding these underlying factors is crucial for developing effective strategies to prevent and counter terrorism.