Apache Tomcat is a Java servlet container and web server used to run server-side Java web applications. It handles requests for web apps built on the Java platform and often sits behind a reverse proxy or load balancer in enterprise environments.
Tomcat matters in cyber security because it is part of the application runtime, not just the front end. If a hosted app has weak authorization, unsafe input handling, or an exposed management interface, an attacker may be able to abuse the application and then impact the Tomcat-backed server layer. In real attacks, Tomcat is commonly targeted through vulnerable web apps, default credentials, misconfigurations, or unpatched components. Defenders should restrict access to administration ports, remove default examples and accounts, patch promptly, and monitor logs for unusual requests, errors, and file access.