Web server Vs Application server

 There you go https://www.youtube.com/watch?v=BcmUOmvl1N8

Then what is Apache Tomcat? web server or application server? Tomcat

https://www.quora.com/Is-Tomcat-a-web-server-or-an-application-server

Tomcat is a web server (handles HTTP requests/responses) and web container (implements Java Servlet, JavaServer Pages, Java Expression Language and Java WebSocket technologies) if we don't consider that we have all the add-ons and plug-ins made available through open source or commercially with Tomcat. Tomcat doesn't implement the complete Java EE API and doesn't have EJB container. Although we could run some applications in tomcat(one could easily argue that it is an application server) it will not be considered as fullfledged applcation server as it lacks some features of application server.

Apache is a web server, which can ideally handle static pages like HTML. 

To handle dynamic pages like php, we may need to load php module in apache configuration file.

Apache Tomcat is a combination of both web and application server, generally called as application server, can handle both static and dynamic pages. 

Of course, it needs java runtime environment as a prerequisite to run dynamic pages like servlets and jsps .