Revision with unchanged content. Web-based information systems, such as search engines, news portals, electronic markets and community sites, provide access to information originating from numerous information providers. The quality of provided information varies as information providers have different levels of knowledge and different intentions. Users of web-based systems are therefore confronted with the increasingly difficult task to select high quality information from the vast amount of Web-accessible information. How can information systems support users to distinguish high quality from low quality information? Which filtering mechanisms can be applied? How can filtering decisions be explained to the user? The book gives an overview about information quality assessment in context of web-based systems. Afterwards, a quality-driven information filtering framework is developed. The framework allows information consumers to apply a wide range of different filtering policies. In order to facilitate the information consumers' understanding of filtering decisions, the framework generates explanations why information satisfies a specific policy. The book targets Web developers who need to handle information quality problems within their applications as well as researchers working on the topic.