The use of patent citations as indicators of innovation has increased dramatically in the last decade. As patents constitute intellectual and economic value, patent citation analysis makes it possible to reveal the hidden innovation activities and knowledge flows between technologies, individuals, firms, industries, or countries. This chapter describes the meaning of the use and analysis of citations in patents and examines how to structure multi-depth patent citations through a network lens. In addition, this chapter recounts the story of the Apple–Samsung lawsuit using the citation network of iPhone’s design patent. Finally, common pitfalls and best practices for using citation data are discussed.