Instrumenting a polyglot microservices application with Elastic APM (Application Performance Monitoring) can significantly enhance observability and performance insights. Using an example application, the process involves setting up Elastic Stack with APM to monitor various services written in different languages like VueJS, Go, NodeJS, Java, and Python. Each service is equipped with Elastic APM agents tailored to its language, enabling distributed tracing and logging for comprehensive system monitoring. Elastic APM tracks transactions, spans, and logs across services, allowing for quick identification and resolution of performance bottlenecks. The setup utilizes Docker containers for deployment and demonstrates diverse ways to configure agents and instrument applications, highlighting the flexibility and depth of Elastic APM. This approach not only improves user experience and business efficiency but also fosters collaboration among development, operations, and security teams by providing a unified perspective on application performance.