Authentication and authorization are two fundamental security concepts used to control access to web applications. Authentication answers the question of who a user is, while authorization determines what that authenticated user is allowed to access or do. For example, a business application may authenticate an employee through a login system and then authorize that employee to access only the dashboard features required for their role. Authentication can be implemented using passwords, sessions, tokens, multi-factor authentication, or external identity providers depending on the application's requirements. Passwords should never be stored as plain text. They should be processed using appropriate password hashing techniques and protected with secure authentication practices. Sessions and tokens also need careful handling to reduce the risk of unauthorized access. Authorization should be enforced on the server rather than relying only on frontend interface restrictions. Hiding a button from a user interface does not prevent someone from directly sending a request to a protected API endpoint. The backend should verify the user's permissions before allowing sensitive operations. Role-based access control can help businesses define different levels of access for administrators, managers, employees, customers, and other user types. Input validation and secure error handling are also important because authentication systems can be targeted by automated attacks. Rate limiting and account protection mechanisms can help reduce abuse. HTTPS should be used to protect communication between users and servers, especially when credentials or sensitive information are transmitted. Businesses should also maintain appropriate logging and monitoring so suspicious activity can be identified. Authentication and authorization are not one-time features that can be ignored after deployment. Security requirements can change as an application grows, and dependencies or infrastructure may need regular updates. A properly designed access-control system protects business information while allowing legitimate users to perform their required tasks. Strong authentication and authorization practices are therefore essential components of secure web application development.