query string

Query string is used to Pass the values or information form one page to another page.
Syntax
Request.QueryString(variable)[(index)|.Count]
Parameters
variable :-
Specifies the name of the variable in the http query string to retrieve.
index :-
An optional parameter that enables you to retrieve one of multiple values for variable. It can be any integer value in the range 1 to Request.QueryString(variable).Count.

For example:-
In page 1:
Drag and drop the one textbox and button control
In page 2:
Drag and drop the one textbox control from tool box and place it on form.
In page one:-


Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
     'bind the textbox values to querystring
        Response.Redirect("Default2.aspx?Textboxvalue=" & TextBox1.Text)

    End Sub
End Class


In page two:-


Partial Class Default2
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        'Get the values from Query string
        TextBox1.Text = Request.QueryString("Textboxvalue")
    End Sub
End Class

hi,
Query string is pass data in url..
example
http://localhost/home.aspx?id=1000

if you want to pass the data from one page to other page...

in first page...
Response.Redirect("mydatapage.aspx?Id=1000");

in mydatapage.aspx.cs page load event

private void Page_Load(object sender, System.EventArgs e)
{
 var id = Request.QueryString["Id"];
}

please refer
http://www.codeproject.com/Articles/5876/Passing-variables-between-pages-using-QueryString
http://www.dotnetperls.com/querystring
hope this will help you.