To secure deployed microservices, multiple security practices are applied at different levels such as authentication, authorization, communication, and infrastructure. First, authentication and authorization should be implemented using secure standards like OAuth 2.0 and JWT (JSON Web Tokens) to ensure only verified users or services can access APIs. Using an API Gateway such as Kong API Gateway or NGINX helps centralize security features like request validation, rate limiting, and authentication before requests reach the microservices. Secure communication between services must be ensured by using HTTPS and TLS encryption to protect data during transmission. Implementing service-to-service authentication with tools like Istio service mesh can further secure internal communication. Additionally, proper access control and role-based permissions (RBAC) should be used so that each service or user has only the required privileges. Sensitive data such as API keys and passwords should be stored securely using secret management systems instead of hardcoding them. Regular logging, monitoring, and vulnerability scanning should also be performed to detect and respond to potential security threats quickly. These combined practices help ensure that microservices remain secure in production environments.