Apart from completeness usability, performance and maintainability are the key quality aspects for Web information systems. Considering usability as key implies taking usage processes into account right from the beginning of systems development. Context-awareness appears as a promising idea for increasing usability of Web Information Systems. In the present paper we propose an approach to context-awareness of Web Information Systems that systematically distinguishes among the various important kinds of context. We show how parts of this context can be operationalized for increasing customers' usage comfort. Our approach permits designing Web information systems such that they meet high quality expectations concerning usability, performance and maintainability. We demonstrate the validity of our approach by discussing the part of a banking Web Information System dedicated to online home-loan application.