Problem calling a servlet from JSP

I know this very basic but I guess I am doing something wrong in my implementation...so please help

Note:I am using eclipse IDE for my development

Project Name:Greeting

Servlet :GreetingServlet.java

package com.test.servlets;
// Import Servlet packages
import javax.servlet.*;
import javax.servlet.http.*;
    
// Import other Java packages
import java.io.*;
import java.util.*;
    
public class GreetingServlet extends HttpServlet {
    
  /**
	 * 
	 */
	private static final long serialVersionUID = 5156856185746908932L;

protected void doPost(HttpServletRequest request,
 HttpServletResponse response) throws ServletException,
 IOException {
 
 // Get parameters from the request.
 String name = request.getParameter("name");
 String email = request.getParameter("email");
 
 // Compute a greeting message
 String message = null;
 GregorianCalendar calendar = new GregorianCalendar();
 if(calendar.get(Calendar.AM_PM) == Calendar.AM) {
 message = "Good Morning";
 }
 else {
 message = "Good Afternoon";
 }
 
 // Set MIME type for the response
 response.setContentType("text/html");
 
 // Obtain a print writer object
 PrintWriter out = response.getWriter();
 
 // Write the content
 out.println("<HTML>");
 out.println("<BODY>");
 out.println("" + message + ", " + name + "");
 
 out.println(" Thanks for registering your email (" + email +
 ") with us.");
 out.println(" - The Pro Java Team. ");
 
 out.println("</BODY>");
 out.println("</HTML>");
 
 out.close();
 }
}

index.jsp

and my web.xml

When i am deploying my project on apache tomcat in Eclipse I am getting "index.jsp" but my index.jsp does not redirect to GreetingServlet.java on submitting.

Error message is as follows:
HTTP Status 404 - /GreetingServlet

--------------------------------------------------------------------------------

type Status report

message /GreetingServlet

description The requested resource (/GreetingServlet) is not available.

In JSP and servlets, / means the root of the web application. In HTML, / means even one level higher. To fix this, use this instead:

Rob Spoor wrote:In JSP and servlets, / means the root of the web application. In HTML, / means even one level higher. To fix this, use this instead:
<form action="${pageContext.request.contextPath}/GreetingServlet" method="post">

It would not must to work if you remove "/" ???
I mean :

That would until you decide to move the JSP to a sub folder and forget to modify either the JSP or the servlet's URL mapping.

Not using the context path to prefix the servlet is fragile and prone to easy breakage as pointed out.

Rob Spoor wrote:That would until you decide to move the JSP to a sub folder and forget to modify either the JSP or the servlet's URL mapping.

Rob could you please elaborate or provide me any link which could enlighten me over this discussion.Cause I would like to understand this mapping concept more..I think its the core of any web project...So any guidance would be highly appreciated.

@Rob and @jhon masco :Thanks to both of you...it worked both the ways..:)

As I have said, Rob's is the correct approach. Anything else may work for now but is fragile and will easily stop working when you make future changes. Do it the right way, not just the way that seems to make it work for now.