This paper examines online identifiers from an economic perspective. It uses conjoint analysis survey techniques to develop empirical data on how users value the attributes of online identifiers. It is concerned in particular with three issues: (1) the degree to which identified subjects value increasing the scope of an identifier, i.e., the ability to use a single identifier to access services offered by several organizations; (2) the degree to which users’ choice may be constrained by switching costs; and (3) the value individuals place on privacy and data security relative to other attributes such as cost or scope. The survey population was located in South Korea. The results indicate that e-mail addresses dominate the world of online identifiers for ordinary consumers; that consumers highly value increased scope (e.g., single sign-on capabilities) and the security of their private data; and that switching costs are high.