The purpose of this paper is to bring the concept of tax havens closer to the reader. There is no precise definition of "tax havens", but they are considered to be characterized by no or only nominal taxes, lack of effective exchange of information, lack of transparency and no substantial activities. First, the very concept of tax havens and their historical development over time is defined. Then the paper lists the division of tax havens that are divided into tax havens without tax burdens, tax havens with low tax burdens, tax havens with a tax burden only on local receipts and special tax havens. After an introductory review of the characteristics of tax havens, a presentation on the definition and characteristics of tax havens begins by analysing the approaches of various institutions. The paper presents and explains the following institutions; Organisation for Economic Development and Cooperation, International Monetary Fund, European Union, G-20 Working Group and Tax Justice Network. Each of these institutions provides it's own view of the concept of tax havens and creates it's own characteristics for recognizing them. In conclusion, today's relationship between tax havens and cryptocurrencies is analyzed as well as its influence on tax evasion and whether there are criteria for combating them.