This book attempts to understand the impact of context collapse on the process of interpersonal interaction by applying an interdisciplinary and interactive perspective. This book systematically explains the impact of context collapse on social behavior by cognitive communication mechanism. Social science and computer system research is the general scope. Social media technology mixes originally heterogeneous audiences into the same context. As a result, people cannot manage multiple identities for online interactions using traditional offline conversation methods. The lack of boundaries in social media platforms in terms of space, time, and social psychology makes it difficult for people to maintain different social environments simultaneously online. Scholars use the concept of "context collapse" to describe how people, information, and norms permeate from one context to another in social media. Context collapse has both advantages and disadvantages and may bring potential positive or negative consequences.