In this talk I will introduce the field of Digital Libraries and explain it through the perspective of the 5S framework of Streams, Structures, Spaces, Scenarios, and Societies. I will also discuss the application of the framework to the definition of a Quality Model for Digital Libraries. Relationships between 5S and the DELOS Reference Model for digital Libraries which is in development will be discussed. Finally, I will briefly comment on some other research efforts that have been conducted in Digital Libraries and Information Retrieval at Federal University of Minas Gerais, Brazil.