Tour operators as an organization have the primary function of organizing travel and creating package arrangements. Their main services are transportation and accommodation. In addition to the main services, they also offer various excursions, tours, sports activities, cultural events, transfers, etc. Safety and constant availability are an important factor in the business of tour operators. Tour operators are also in charge of promoting sustainable tourism and environmental protection. Through their activities, they contribute to tourism development, support local communities and connect service users with specific destinations. By developing trends, tour operators come up with challenges that they need to fulfill in order to justify the expectations of users. Through promotion, they reach a larger number of their users and thus increase the sale of package arrangements. In order for their promotion and then sales to be successful, tour operators use the creation of various catalogues and advertising on the internet. The subject of research in this paper are the functions of tour operators, which are based on the reservation and organization of all necessary services for travel, providing them with a complete travel experience. An important role is also played by the protection of tourist consumers, package-arrangement users, which is reflected above all in the specificity and complexity of travel organizer products compared to material products, goods intended for general consumption. The travel organizer's product is specific considering its extreme importance in the life of every person. In order to better understand the entire issue related to the participation of travel organizers in world tourism, it is necessary to observe their historical development within the framework of certain development phases that they have gone through until today.