Rural areas are influenced by many natural, social and economic factors. The historical conditions of social development, such as the rate of population growth, low yields and chronic food shortages, leading to the development of less useful areas with low production potential for agricultural purposes, have had an impact on the current state of rural areas. In addition, there is considerable fragmentation of agricultural land in these areas and a focus on production to meet farmers’ own needs. Scientific literature comprises many proposals to define agriculturally unsuitable land in relation to the marginal, problem or abandoned land. This depends mainly on the research discipline, the authors and the approach to the issue under discussion. This paper aims to review the terminology and characterisation of land unsuitable for agriculture in Poland and selected European and Asian countries. Moreover, studies have been conducted into the reasons for the expansion of these areas and the ways of their development (e.g., performing forestry functions, growing crops for energy purposes, promoting tourism and recreation as well as pedestrian or hippie bicycle routes, creating ecological areas, terracing the slopes), which in the result is the main priority of agricultural development and improvement of the spatial structure of farms. Realising the specific functions the presented land is intended for should determine the direction of changes in their alternative development. All solutions for the development of these areas should be managed with a necessary consideration of social, economic and environmental aspects.