Exploratory spatial data analysis (ESDA) is an extension of exploratory data analysis (EDA) to detect and understand the properties of spatial data. ESDA is an important research field in geographic information science (GIScience) because we now live in a data-rich world and a vast and increasing amount of information on geographical phenomena is recorded digitally as spatial data. Adopted by many subdisciplines of geography and other disciplines (e.g., epidemiology), ESDA has made enduring contributions to the development of GIScience and geography. Therefore, ESDA is an important topic in this Encyclopedia. This entry discusses three related topics: (1) EDA, (2) traditional ESDA, and (3) the potential future directions of ESDA.