What is the difference between application server and web server?

Question

What is the difference between application server and web server?

Answer 1

• web server: for every URL, it returns a file. That's all it does. The file is static content, meaning, it is stored somewhere in the server, before you make your request. Most popular web servers are apache http and nginx.
• application server: for every URL, it runs some code, written in some language, generates a response, and returns it. The response doesn't exist in advance, it is generated for your particular request, that is, it is dynamic content. Application servers are different for each language. Some popular examples are tomcat/jetty for java, uwsgi/gunicorn for python.

Almost every page you visit uses both. The static content (eg, images, videos) is served by the web server, and the rest (the parts that are different between you and other users) are generated by the application server.