Seasonality is the intrinsic characteristics of tourism. Many tourist destinations are suffering from this phenomenon every year, so tourism strategies from public and private sectors place considerable emphasis both on extending the existing tourist season and on developing new markets for off-peak season. Seasonality is described as a temporal imbalance in tourism, and may be expressed in terms of visitors number, the expenditure of visitors, all forms of transportation, employment and admission to attractions. Seasonality impacts on all aspects of supply-side behaviour in tourism, including marketing, the labour market, business finance, stakeholder management, and all aspects of operations. Therefore, it is widely seen as a "problem" to be "tackled" at policy, marketing and operational level. Specific problems include a longer season to gain enough profit to pay capital costs, lack of labour in the peak season, high unemployment in off-season. However, some researchers think that, in certain circumstances, seasonality in demand offers opportunities to rural tourist destinations where tourism jobs frequently complement other areas of traditional employment such as forestry, fishing or agriculture. Much attention has been paid and much effort has been made to overcome seasonality in tourism. There are different ways in reducing seasonality, such as launching additional seasons, diversifying markets, reducing prices and providing off-season activities. Although seasonality may be an almost universal characteristic of tourism, it varies considerably in different places. To describe the nature of seasonality and analyse the importance of seasonality, researchers have developed many measures such as seasonality indicator, Gini coefficient for describing characteristic of seasonality and models such as time series approaches, modern econometric ways for tourism demand forecasting.