Apache Tomcat is an open source software implementation of the Java Servlet and JavaServer Pages technologies. It offers “pure Java” HTTP web server environment for Java code to run. Apache Tomcat powers numerous large-scale, mission-critical web applications across a diverse range of industries and organizations.

In general, Apache Tomcat server is used for hosting web application that is executed on a web browser. There is some basic difference between Tomcat and Apache webserver. If you are going to serve only static (such as HTML) pages, then Apache webserver would be sufficient, but if the pages being (dynamically) served are in JSP/Servlet then you need a container that can interpret them, and thus we use Tomcat. Apache Tomcat is actually a servlet container that can be used as a standalone webserver.