The internet was expected to democratize information access by eliminating traditional gatekeepers and enabling unlimited choice. Early visions anticipated that reduced distribution costs would disperse attention across countless sources, creating diverse information ecosystems. However, empirical evidence increasingly challenges this optimistic narrative by showing that systematic patterns continue to shape how information is produced, circulated, and consumed online. This dissertation investigates these patterns by examining three emergent properties of digital information environments. First, I examine how concentrated the information ecosystem is across multiple levels of analysis. Although these systems evolve over time, with user bases changing and different sources temporarily dominating attention, such fluctuations still give rise to consistent patterns of concentration. This concentration emerges simultaneously at the levels of domains, individual URLs, users, and the distribution of both sharing and exposure. In other words, despite continual change in who participates and what content circulates, a small subset of sources and actors persistently captures a disproportionate share of visibility. While concentration captures how attention becomes unevenly distributed, it does not reveal whether different groups encounter the same concentrated set of sources. The second chapter addresses this by examining how information exposure varies across demographic groups and by tracing how major events intensify these divides. In doing so, it shows that segregation, particularly along age and gender lines, increases over time. The third chapter analyzes how platform governance transitions affect information quality. Following Twitter and X’s October 2022 ownership change, statistically significant declines in information quality emerged through shifts in market share. Low-quality sources expanded their visibility while high-quality sources declined. These outcomes were produced both by changes in user composition and by platform-level policy or algorithmic adjustments, demonstrating that governance structures directly shape the credibility and distribution of circulating information. The remainder of this dissertation will be devoted to understanding the mechanisms that produce these emergent phenomena of concentration and segregation. By incorporating more detailed, user-centric data from the National Internet Observatory, I will be able to test whether these patterns intensify, weaken, or take different forms when examined with human-level behavioral data rather than solely platform-centric measures.