Difference between a servlet and a proxy servlet

Question

What is the difference between a servlet and a proxy servlet (or in short what does proxy mean in this context)? How/Why routing backend calls though a proxy servlet, instead of http calls, in AJAX/Javascript helps resolving cross domain issues?

Answer 1

As far as I know, ProxyServlet is the one which does not serve the request by itself but seeks another resource (possibly in the same war/different war/even different machine). However, the calling client is unaware of this delegation.

HTTP Proxy Servet is a nice example of ProxyServlet