In order to avoid naming conflicts in controls, ASP.NET 2.0/3.5 used ClientID's, which made each control generate the ID attribute unique to that pageHowever the ID's generated were long and unpredictable.

ASP.NET 4, through the new ClientIDMode property, now gives control back to the developer over the ClientID's generated by ASP.NET controlsIn this article, we will explore this new property.