TomCat

The Apache Tomcat software is an open source implementation of the Java Servlet, JavaServer Pages, Java Expression Language and Java WebSocket technologies. 

Servlet

Java server side technology which will handle request and response. It doean’t understand HTTP it is just a middle layer.

JSP (Java server page)

Is a java Representationa layer instead of reular HTML file. used to write java code in HTML tags to dynamically represent data to user.

Components

Catalina

Catalina is Tomcat's servlet container. which handles the requests between the Servlet and the rest of tomacat (container) such as URLs routing to different Servlet

Coyote

Coyote is a Connector component for Tomcat that supports the HTTP 1.1 and 2 protocol as a web server. This allows Catalina, nominally a Java Servlet or JSP container, to also act as a plain web server that serves local files as HTTP documents. Allowing the server to serve static files

Jasper

Jasper is Tomcat's JSP Engine. Jasper parses  JSP files to compile them into Java code as servlets (that can be handled by Catalina). At runtime, Jasper detects changes to JSP files and recompiles them.

Tomcat Architecture

Refrences

Apache Tomcat®

The Apache Tomcat ® software is an open source implementation of the Jakarta Servlet, Jakarta Server Pages, Jakarta Expression Language, Jakarta WebSocket, Jakarta Annotations and Jakarta Authentication specifications. These specifications are part of the Jakarta EE platform. The Jakarta EE platform is the evolution of the Java EE platform.

https://tomcat.apache.org/