Hi, I want to know what is main difference between Single Threaded and MultiThreaded Client-Server?
I want to create a client server chat application.

Server Form consist:
1 Textarea(text area) (to display text)
1 sendarea(text area) (to type the text to send)
1 Send button (to send the text which is typed in sendarea) it sends to client
1 exit button (closes application)

Client Form consist:
1 Textarea(text area) (to display text)
1 sendarea(text area) (to type the text to send)
1 Send button (to send the text which is typed in sendarea) it sends to server
1 exit button (closes application)

Please guide me!!

You need to wait for input from the local user and at the same time you need to wait for input from the remote end, and at the server you also need to wait for new client connections. Although it is technically possible to do that in a single thread it would be very hard. In practice this kind of applications is always multi-threaded.