Principles that guide how a classification system should be structured have existed for more than a century. Traditional classification principles can be of great value for the design of classification schemes directories on the web. However, there are differences between the library context in which these principles originated, and the web. This thesis aims at investigating how changes in the context of classification affect the application of traditional principles of classification on the web. Another purpose is to see what implications this has for the design of classification schemes on the web. This thesis sets out to answering the following questions: Which principles are central to forming a functional classification system? What characteristics, with relevance to classification, separate the web-environment from the traditional library context? How do differences between these contexts influence principles and functions of classification on the web? What does this imply for system design on the web? This is attained by a study of literature. A systems-theory perspective is applied, which means that the study is set in a contextual framework, and focuses on the systematic order of classification systems. Electronic documents on the web have, in contrast to the librarys paperbased documents, no physical locality. Hypertext, which characterizes the web, has a non-sequential structure. These are keys factors that separate the flexible web-environment from the more static library context. As a consequence, several of the historical difficulties of library classification disappear. There is, for instance, no need for shelf location on the web. Virtual documents can have multiple locations to reflect a documents many aspects. The following conclusions are made: Due to the webs flexibility the principles that bring flexibility to a classification system lose some of their importance on the web, while the principles that generate stability and predictability remain valuable. Those last principles are therefore useful for system design on the web. The webs "inherent" flexibility should also be considered in the design of a classification scheme on the web. It is shown here that browsing is suitable for the inexperienced user in seeking information on the web. An implication is that classification schemes on the web should be designed to support browsing. The browsing function of classification gains more importance on the web. Hierarchy, especially digitized hierarchy, supports browsing. Principles that generate a hierarchical structure are therefore useful for system design on the web.