What is Web server?
A Web server can process HTTP requests and respond with HTML pages, provided the requests are handled by server side programs
It uses HTTP protocol to transmit the request/responses. Here Web server handled both request/response and business logic. This is more rigid design.
A web transaction using web server will be like this as below,
Browser (click operation to display some results on a grid> ==> Request goes to web server (Apache HTTP server) ==> Database