View State is the method to preserve the Value of the Page and Controls between round trips. It is a Page-Level State Management technique. View State is turned on by default and normally serializes the data in every control on the page regardless of whether it is actually used during a post-back.

A web application is stateless. That means that a new instance of a page is created every time when we make a request to the server to get the page and after the round trip our page has been lost immediately

Features of View State

Retains the value of the Control after post-back without using a session.
Stores the value of Pages and Control Properties defined in the page.
Creates a custom View State Provider that lets you store View State Information in a SQL Server Database or in another data store.
Advantages of View State
Easy to Implement.
No server resources are required: The View State is contained in a structure within the page load.
Enhanced security features: It can be encoded and compressed or Unicode implementation.