This dissertation examines the impact of a digital information environment on media diversity and the types of political news people consume. The study is based on four sub-studies, two of which focus on methodological and conceptual challenges faced by researchers in studying media diversity in the digital environment. In Chapter 2, a systematic literature review of over 200 academic articles was conducted to identify gaps in existing research, revealing that most studies on media diversity rely on outdated ideas from an era dominated by mass media, and do not consider the impact of personalization and fragmentation. Chapter 3 provides an overview of the challenges associated with collecting digital traces for research purposes, including data access, privacy, and usability of data collection tools. The chapter offers recommendations on how researchers can collect data from multiple platforms and devices to improve their studies. Chapter 4 and 5 examine the impact of fragmentation and personalization on news diversity. The main findings of these studies show that fragmentation leads to less diverse news consumption, whereas personalization leads to more niche and diverse consumption. Overall, the dissertation concludes that the digital environment has fundamentally changed the way people engage with news and that media diversity research needs to evolve to reflect these changes, considering aspects such as personalization and fragmentation.