what is the actual use of ScriptManager

Script Manager[^]

script manager lets you not to refresh whole page instead a part of page.
but before using script manager make sure which control does not work correctly inside script manager
for example menu control does not work correctly inside script manager.
Thanks pradeep lakhina

Main use of Scriptmanager is Support the make the AJAX controls functional,as it manages Each and every aspect of the controls. For e.g. if we take an update panel and there is piece of code which takes lots of time to execute as there might be some functionality to be achieved we can set the Execution time out to make the prolonged methods process successfully.
Secondly if there are some java scripts we are using we can load those at one time when the scriptmanager is loaded.
Each and Every event related to ASYNC post back can be traveresed by scriptmanager which makes error thrown due to AJAX manage able instead on getting JAVASCRIPT of timed out or requestparameter thrown error etc.