In times when users need to process an ever increasing amount of information to perform more complex tasks in less time, the introduction of context in computer systems is becoming a necessity. Context is "the interrelated conditions in which something exists or occurs" or "what underlies the ability to identify what is or is not relevant in a given situation". Context-Sensitive Systems (CSS) are those that use context to provide information and/or services relevant to a task execution. Designing a CSS is not trivial, since it is necessary to deal with issues associated to: which information to be considered as context, how to represent it, how it can be acquired and processed and how to design the context usage into the application. This book discusses the usage of context in computer systems and presents a framework to support the design of CSS fo different domains. It is composed by four elements: a reference context management architecture; a context metamodel to guide context modeling; a set of UML profiles; and a context process with guidelines for activities related to context specification and CSS design.