In my thesis I will deal with the problem of terrorism. I chose this as the topic of my essay because it is a very important problem of the 21st century and it concerns everybody. It has always been around, but the extent to which it has developed in the course of time is very frightening nowadays. It is not only the problem of the countries that has been attacked by terrorists, but the problem of everybody living in this world in the 21st century. I will discuss the problem of defining the term properly and then I will give a short overview of the changes that took place in the meaning of the term as well as in methods and means. Then I will talk about terrorism in history.