Apache Tomcat is a widely used open-source server for running Java-based web applications, developed by the Apache Software Foundation. Originally created by Sun Microsystems and donated to the foundation in 1999, Tomcat functions as a Java Servlet Container, supporting Java EE Servlet specifications and serving dynamic content through Java Server Pages (JSP) and Java servlets. It is favored for smaller applications due to its lightweight nature and ease of administration, running efficiently within a Java Virtual Machine (JVM). The architecture of Tomcat includes a Catalina server, services, connectors, and containers that process requests and manage workloads through worker threads. Tomcat can operate as both a standalone web server and in collaboration with Apache HTTP Server, using connectors like HTTP and AJP to handle requests. Monitoring key performance metrics such as throughput, thread pool utilization, errors, and JVM memory usage is crucial for maintaining Tomcat's efficiency, with tools like JMX providing insights into these metrics. Efficient management of thread and memory resources is vital to avoid bottlenecks and errors, ensuring Tomcat serves applications effectively.