— A user interface description language (UIDL) consists of a specification language that describes various aspects of a user interface under development. A comparative review of some selected user interface description languages is produced in order to analyze how they support the various stages of user interface development life cycle and development goals, such as support for multi-platform, deviceindependence, modality independence, and content delivery. There has been a long history and tradition to attempt capturing the essence of user interfaces at various levels of ion for different purposes, including those of development. The recent return of this effort today gains more attraction, along with the dissemination of XML markup languages, and gives birth to many proposals for various user interface description languages. Consequently, an in-depth analysis of the salient features that make these languages different from each other is desired in order to identify when and where t...