An application server
I'm now using the built-in apache web server just to terminate the TLS connection and to take advantage of the automated certificate renewal feature that my hosting provider offers.
Application server
Apache acts as a reverse proxy for my actual web server, a simple HTTP server written in C listening on port 8080.
All the actual application logic lies inside the C program, which uses a database.
You could say that the C program is my "application server".