The UP describes work activities, such as writing a use case, within disciplines
(originally called workflows).3 Informally, a discipline is a set of activities (and
related artifacts) in one subject area, such as the activities within requirements
analysis. In the UP, an artifact is the general term for any work product: code,
Web graphics, database schema, text documents, diagrams, models, and so on.
There are several disciplines in the UP; this book focuses on some artifacts in
the following three: