What is Session and View state in asp.net c#

Various state management techniques

A. Client-side State Management: 

• View State
• Hidden Field
• Cookies
• Control State

B. Server-side State Management

• Session
• Application Object
• Caching

1. View state 

View State is a technique to maintain the state of controls during page post-back, meaning it stores the page value at the time of post-back (sending and receiving information from the server) of your page and the view state data can be used when the page is posted back to the server and a new instance of the page is created.

Sample Code 

1. namespace Test  
2. {  
3.     public partial class _Default : Page  
4.     {  
5.         int TestCounter = 0;  
6.         protected void Page_Load(object sender, EventArgs e)  
7.         {  
8.             if(!IsPostBack)  
9.             {  
10.                 TextBox1.Text = "0";  
11.                 TextBox2.Text = "0";  
12.             }  
13.         }  
14.         protected void Button1_Click(object sender, EventArgs e)  
15.         {  
16.             //With out View State  
17.             TestCounter = TestCounter + 1;  
18.             TextBox1.Text = TestCounter.ToString();  
19.   
20.             if (ViewState["counter"] != null)  
21.             {  
22.                 TestCounter = (int)ViewState["counter"] + 1;  
23.                 TextBox2.Text = TestCounter.ToString();  
24.             }  
25.             ViewState["counter"] = TestCounter;  
26.   
27.         }  
28.     }  
29. }  

View State advantages: 

• Very easy to implement.
• Stored on the client browser in a hidden field as a form of Base64 Encoding String not encrypted and can be decoded easily.
• Good with HTTP data transfer

View State disadvantages:

• The performance overhead for the page is larger data stored in the view state.
• Stored as encoded and not very safe to use with sensitive information.

Session State :-

in session state one we stored value in session then we can use it on another page but in view state we can not use stored value on another page.

1. //Stored Textbox value  
2. Session["Counter"] = TextBox3.Text;  
3.   
4. //Stored Dataset  
5.    
6. Session["ds"] = dsData;  
7. Session variables are stored in a SessionStateItemCollection object that is exposed through the HttpContext.Session property.