According to the Global Terrorism Index (GTI), which tracks the number of terrorist attacks, deaths, and injuries worldwide, there were 5,835 terrorist attacks in 2021. However, it's important to note that different organizations may use different definitions of terrorism and may track different types of attacks, so the exact number can vary depending on the source.
For example, the National Counterterrorism Center (NCTC) of the United States defines terrorism as "the use of force or violence against persons or property in order to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives." Based on this definition, the NCTC reported that there were 10,900 terrorist attacks worldwide in 2019.
It's also worth noting that the reporting of terrorist attacks can be complex, as some incidents may not be officially classified as terrorism, and there can be discrepancies in the data collection and reporting methods of different organizations. Additionally, the number of reported attacks may be influenced by factors such as media coverage and the availability of information from certain regions.
Overall, while it's possible to provide estimates of the number of terrorist attacks in a year based on available data, the exact numbers can vary depending on the definition used and the data sources consulted.