Online identifiers in everyday life

Identifiers are an essential component of online communication. Email addresses and instant messenger usernames are two of the most common online identifiers. This dissertation focuses on the ways that social, technical and policy factors affect individual's behavior with online identifiers.Research for this dissertation was completed in two parts, an interview-based study drawn from two populations and an examination of the infrastructure for managing identifiers in two large consumer services. The exploratory study examines how individuals use online identifiers to segment and integrate aspects of their lives. The first population is drawn from employees of a financial service firm with substantial constraints on communication in the workplace. The second population is drawn from a design firm with minimal constraints on communication. The two populations provide the opportunity to explore the social, technical, and policy issues that arise from diverse communication needs, uses, strategies, and technologies. The examination of systems focuses on the infrastructure that Google and Yahoo! provide for individuals to manage their identifiers across multiple services, and the risks and benefits of employing single sign-on systems.This research contributes to our understanding of the ways that identifiers shape online self-representation and communication. Specifically, interview data highlight the ways in which individuals' preferences for the creation and management of identifiers conflict with external factors. These conflicts lead to frustration, arbitrary decisions, and complicated management issues. This thesis concludes with recommendations for system designers and policy implementers.