Here is the pretty good example:
When I typed the "abc" google started to give me suggestions. Its Looks good :-)
The same thing you can achieve in you web application using "AutoCompleteExtender" control.
Let me show you some example:
I wanted to display three more letter as a postfix whatever i am typing...
eg.. prashaXBZ // here laxt there XBZ is my suggestion
For that I will create one web method & it will give me random character.
//web method code
-----------------------------------------------------------------------------
Here is the my .aspx page code
HERE
MinimumPrefixLength="3" --> it will give you suggestion after three character.
CompletionSetCount="10" --> Number of suggestion you want to see
ServicePath="AutoComplete.asmx" --> My Service virtual path
ServiceMethod="GetCompletionList" --> My service method.
There we go...