Tourism as a system object of study. Tourism - an open socio-economic system. Modern definitions of the concept of "tourism". Distinctive characteristic features of tourism. Statistical definition of tourism. Existing classifications in tourism. The essence and purpose of classification; Factors affecting tourism as a system. Functions of tourism. The main factors affecting tourism: static (natural-climatic, cultural-historical) and dynamic (political, socio-demographic, financial, economic and logistical). External and internal factors affecting tourism