The technological evolution of networks together with the development of positioning systems has contributed to the emergence of numerous location-based services. Services related to this expanding area will become of major technical as well as economical interest in the coming few years. This aroused a great deal of interest from the scientific community at large and specifically from those studying these services and their diverse requirements and constraints. One of the direct consequences in the database field is the appearance of new types of queries (mobile queries issued from mobile terminals and/or requesting information associated with moving objects such as vehicles). Our objective in this chapter is to present a comprehensive survey of the field of research work related to mobile queries, with particular attention to the location issue.