Web Server vs Application Server

A web server handles HTTP requests and serves static content such as HTML, CSS, images and JavaScript files. It is also commonly used as a reverse proxy that passes other requests on. Apache HTTP Server and Nginx are the best-known web servers.

An application server runs the application's code to build dynamic responses: it executes business logic, talks to databases and manages sessions and transactions. Examples are Tomcat, WildFly and Node.js or Gunicorn processes. In a typical setup Nginx sits in front, serves static files itself and forwards dynamic requests to the application server.