A PostgreSQL role is the database identity used to authenticate a user, service, or application and to define what that identity can do. Roles can own objects, read or write tables, create schemas, manage other roles, and inherit privileges from group roles. In practice, roles are the core of PostgreSQL access control.
This matters in cyber security because database compromise is often limited or amplified by role design. An attacker who reaches PostgreSQL with a low-privilege role may only view a narrow set of data, while a reused admin role or overly broad service account can expose entire databases. Defenders use separate roles for applications, least-privilege grants, strong passwords or certificate auth, and regular audits to reduce blast radius. In attacks, stolen credentials or misconfigured roles are a common path from initial access to data theft.