Cookies Vs Sessions

As far as my knowledge is concerned, cookies are stored on client side where as sessions are server variables. The storage limitations are also there (like IE restricts the size of cookie to be not more than 4096 bytes). We can store only a string value in a cookie where as objects can be stored in session variables. The client will have to accept the cookies in order to use cookies, there is no need of user's approval or confirmation to use Session variables cos they are stored on server. The other aspect of this issue is cookies can be stored as long as we want(even for life time) if the user accepts them, but with session variables we can only store something in it as long as the session is not timed out or the browser window is not closed which ever occurs first.

Coming to usage you can use both cookies and session in the same page.

We should go for cookies to store something that we want to know when the user returns to the web page in future (eg. remember me on this computer check box on login pages uses cookies to remember the user when he returns). Sessions should be used to remember something for that particular browser session (like the user name, to display on every page or where ever needed).

how to write and read cookies.

This eample code belongs to web site www.gotdotnet.com visit the following link for full example code and demo.

http://samples.gotdotnet.com/quickstart/aspplus/doc/stateoverview.aspx

Protected Sub Page_Load(sender As Object, e As EventArgs)
If Request.Cookies("preferences1") = Null Then
Dim cookie As New HttpCookie("preferences1")
cookie.Values.Add("ForeColor", "black")
...
Response.AppendCookie(cookie)
End If
End Sub

Protected Function GetStyle(key As String) As String
Dim cookie As HttpCookie = Request.Cookies("preferences1")
If cookie <> Null Then
Select Case key
Case "ForeColor"
Return(cookie.Values("ForeColor"))
Case ...
End Select
End If
Return("")
End Function

How to write and read session variables.

This example belongs to www.eggheadcafe.com visit the following link for quick summary and list of FAQs on Session State.

http://www.eggheadcafe.com/articles/20021016.asp

Basic use of Session in ASP.NET (C#):

STORE:
DataSet ds = GetDataSet(whatever parameters);
Session["mydataset")=ds;

RETRIEVE:
DataSet ds = (DataSet)Session["mydataset"];



web application is stateless protocol.
If we want some information to be travle from one page to another page in asp.net then we can use cookies as well as session.
cookies:-with the help of cookies we cal transfer the information from one page to another page but the value should be simple text,bt session can use any type of serialize data.
only 20 cookies for one host
session may be lot.
we can use multiple cookies.
cookies value can be change by user but session value is vary secure.