ViewState : It is a inbuilt structure which will hold values for multiple requests in the same page.
1. No servers resources are required.
2. It is very simple to use.
3. Values are more secure as hashing, encoding and compression are done.
4. Good for caching.
1. As large values are stored the page loading and performance will decrease.
2. Even though view state values are hashed, still they can be retrieved as they are stored in hidden fields on the page.