Usernames

A username, also called a handle, login name, or screen name, is a textual identifier that a user selects to represent themselves on a computing system or online service. It serves primarily as a unique identifier for authentication and as a visible alias within a community. In many systems the username is distinct from the display name; the latter is a user-visible label that may be changed more freely and may not be unique.

Common formats for usernames include letters, digits, underscores, hyphens, and periods. Rules vary by platform: some require the username to start with a letter, others allow digits at any position. Length limits apply, and case sensitivity depends on the system—some treat "User" and "user" as the same, others as different. For privacy, many users choose pseudonyms rather than real names. In some contexts, the username is also used as the login credential, while in others it is primarily a public alias.

Choosing a username involves considerations of memorability, availability, and safety. A good username is easy to recall and type, communicates a chosen persona, and avoids revealing sensitive information. It should steer clear of offensive content and minimize the use of personal identifiers if privacy is a concern. Users may reuse a username across services, though some platforms enforce uniqueness per service. When a preferred name is taken, many services offer alternatives or suggest modifications.

Impact and governance: usernames may be tied to accounts and can be involved in branding, impersonation concerns, and moderation. Platforms implement policies regarding impersonation, name changes, and allowed content. Privacy considerations include the potential for a username to be linked back to real identity across services. Historically, usernames emerged from early multi-user systems and have evolved into widely used social-media handles.