Hardcoded credentials refer to usernames, passwords, or other authentication secrets that are directly embedded into a software's source code. This practice is risky because if attackers gain access to the code, they can easily extract these credentials and compromise systems or data. Hardcoded credentials are often used for convenience during development, but they should be replaced with secure methods, such as environment variables or secret management tools, before deployment. Leaving hardcoded credentials in production code is considered a critical security vulnerability and can lead to unauthorized access, data breaches, and compliance violations.