hi, Web Server serves static HTML pages (or gifs, jpegs, etc.), and can also run code written in CGI, JSP etc. A Web server handles the HTTP protocol. Eg of some web server are IIS or apache
An Application Server is used to run business logic or dynamically generated presentation code. It can either be .NET based or J2EE based (BEA WebLogic Server, IBM WebSphere, JBoss).
A J2EE application server runs servlets and JSPs (infact a part of the app server called web container is responsible for running servlets and JSPs) that are used to create HTML pages dynamically. In addition, J2EE application server can run EJBs - which are used to execute business logic.
An Application server has a 'built-in' web server, in addition to that it supports other modules or features like e-business integration, independent management and security module, portlets etc.
A computer that stores Web documents and makes them available to the rest of the world. A server may be dedicated, meaning its sole purpose is to be a Web server, or non-dedicated, meaning it can be used for basic computing in addition to acting as a server.
A software server that lets thin clients use applications and databases that are managed by the server. The application server handles all the application operations and connections for the clients