ViewState is one of the state managements in the ASP.NET, as such here are a few items for better understanding of the VIEWSTATE:

  1.  Understanding ASP.NET ViewState [MSDN]
  2. TRULY Understanding ViewState [InfiniteLoop’s Blog]
  3. Understanding View State in ASP.NET [aspAlliance]
  4. ViewState: All You Wanted to Know
  5. The ASP.NET ViewState [MSDN Magazine]