This paper introduces Periphoscape, a browser extension designed to broaden users’ perspectives by providing related information alongside referenced Wikipedia articles. Rather than merely listing related articles, Periphoscape presentsWikipedia categories that encapsulate sets of related information. Furthermore, the rationale behind the selection of related information is also made transparent. This approach facilitates easier comprehension and enhances the user’s grasp of related concepts. To offer more comprehensive insights, Periphoscape employs approaches such as utilizing previously overlooked incoming links and selecting articles that, while not relevant at the article level, share similarities at the subtopic level. Additionally, it utilizes the structural features of the network of articles and their categories to effectively select useful information. The utility of the information uncovered by Periphoscape has been validated through user experiments with actual data, confirming its effectiveness in enhancing user understanding.