abstract: The paper reviews the farming system definition, methodology of farming system classification (typology) at farm or an area unit (mostly NUTS 5; NUTS – Nomenclature of Territorial Units for Statistics) level using different types of data (survey, census and remote sensing data), and importance of this typology. The diversity of farming systems is a crucial issue in several studies related to agro-ecosystem and environmental management, policy implementation and rural development. In performing the farming system typology within a farmland area, hierarchical classification of respective units has been adopted in which the three following levels of the classification are considered: 1) the main type level, 2) the more oriented type level, and 3) the specific type level. Study of the farming systems typology at a spatial scale can be performed using expert or statistical methods. The last are mainly used to distinguishing specific types of farming systems within a more oriented farming system. The sampling of farms considered for the farming system typology may rely on geographical or administrative stratification. Data on the sampled farms are collected through surveys of farmers or national and EU (European Union) databases (e.g., the FADN database; FADN – Farm Accountancy Data Network). For farming system diversity assessment at an area unit level, data should be aggregated at the respective area unit scale. Expert methods are based on knowledge of guide researchers or agricultural extension experts supported by land cover maps and recorded databases. Farming system types are inferred from the statistical characteristics of the sampled farms or the entire set of the area units, obtained through multivariate methods such principal component analysis and cluster analysis. Assessment of farming system diversity and typology have become increasingly important in recent years because of their usefulness in developing flexible policies for public interventions and for the effective planning, discussion and support of proper pathways for the development of multifunctional and sustainable agricultural and rural areas. Comprehensive approaches that take into consideration various sources of data and track spatio-temporal changes in farming systems are highly valuable tools for achieving the sustainable development of rural areas.