Scriptmanager control is the central heart of Ajax. They manage all the Ajax related objects on the page. Some of the core objectives of scriptmanager control are as follows:-

► Helps load core Ajax related script and library.

► Provides access to web services.

► ASP.NET authentication, role and profile services are loaded by scriptmanager control.

► Provided registration of server controls and behaviors.

► Enable full or partial rendering of a web page.

► Provide localization features.

In short , any Ajax enable page should have this control.