**1. Introduction**

Negative consequences of tourism development were acknowledged and researched for many years [1], including issues of overcrowding, carrying capacities [2,3] and guests-residents relationships or community antagonism [4]. That is why the term "overtourism" might be perceived as old wine in a new bottle [5]. According to Capocchi et al. [6] p. 10, what is new is mainly the level of awareness of the possibly damaging effects of the continual quantitative growth of mass tourism. Phi [1] added that the current overtourism debate continues many of the issues on tourism development that were undertaken previously, yet, now, they take place in a much wider range of destinations, and they are much more complex, which is a guarantee that they will be explored further [7]. However, it is often justified to perceive "overtourism" as a term that enriches our terminology and our knowledge about tourism development, since it appeared as a result of changed conditions of contemporary tourism development and it is intended to illustrate the process typical for the second decade of the 21st century [1,5]. The negative impact of tourism development has recently been associated with terms such as anti-tourism movements, tourism-phobia, tourist-phobia and overcrowding [7] p. 25. Higgins-Desbiolles et al. [8] p. 16 described the conflicts represented by overtourism as a wake-up call as tourism should be reclaimed from an industry that has defined it as a business sector to accumulate their profit, to a human endeavor based on the rights and interests of local communities in welcoming tourists. While causing reductions in the quality of service of a tourist destination and rejection by the local population, overtourism spoils the positive economic and social results produced by the tourism sector [9]. In numerous popular tourist destinations where the harmful effects of overtourism occurred, any previous consensus on the desirability of continuous quantitative tourism growth for the sake of maximizing the economic benefits of tourism, without fully considering the side effects that can be destructive to the social, cultural and ecological environments, has come under intense pressure from the civil society and local populations.

The main aim of the paper is to summarize different approaches and points of view on the overtourism issue, including searching for reasons for tension between tourists and visitors in particular destinations. They are presented partially in tourism literature but also in the literature dealing with urban studies, sustainable development and other areas. This aim was achieved through a literature review and the deduction method. As a result, by summing up pieces of information already presented but in a very scattered way in the contemporary literature, it was possible to present two different approaches to overtourism as well as strengths and weaknesses of the contemporary knowledge on this issue. Referencing many different scientific sources enabled capturing of few factors possibly supporting overtourism and tourism-phobia that were not analyzed in most of the contemporary publications. Those factors are mainly connected with the way tourism develops in particular cities. It was assumed that in the case of contemporary cities, tourism development involves a bigger number of inhabitants with much different attitudes and expectations than in traditional tourism resorts. Those inhabitants are confronted with tourists' behavior that might be evolving quickly, but often does not consider local society as more than a group of people delivering services for visitors. Growing awareness and education of tourists in many cases may not help this situation as those aware tourists in their search for authentic experiences often disrupt local people's everyday life. The most important scientific output of the paper is connected with significant gaps in the scientific knowledge which were identified. Those gaps are to be perceived as the most urgent directions for future research within the field. Additionally, some practical recommendations are offered.

The paper is organized as follows: in the first part of the paper, the notion of overtourism and different approaches to the issue are deliberated. In the next parts, potential reasons of overtourism are presented starting from those that are acknowledged in most of the publications, such as growing number of tourists or new solutions in IT business, through those that are underlined from time to time, such as management mistakes in particular destinations, and finishing with those that are expressed very rarely, such as growing popularity of city tourism and the shift from 3S to 3E tourism. The paper ends with conclusions and limitations.
