The process of designing systems or products largely depends on a number of decisions, like "who do I design for?", "what should my product do?", "what are the user requirements?" etc. The developing teams usually base their decisions on experience and/or heuristics and this is particularly the case, in the development of online products and especially online exhibitions. The different solutions are frequently case studies of specific museums or institutions that wish to provide online content to actual or possible visitors. In addition, the interdisciplinary nature of the endeavor, involving museology, technology but also education, poses important design problems. In the following sections, we present a generic methodology for the design of online exhibitions, using top-down processes and transferable findings across museum types that wish to assist the designers during the early decision stages. This paper provides an introduction to the field, emphasising its interdisciplinary nature and reviews related work in the area of online exhibition design. It also presents an overview of the methodology, elaborating on the individual methodology steps; in particular, the processes for determining the visitors' perception of the museum (degree of museumness); the museum needs that require to be supported; the educational approach to be adopted; the relevance to life-long learning activities; the approach to adaptivity; and user involvement have been reviewed.