What is on line check before departure,what is procedures for it?

Checking in online (no sooner than 24 hours prior to departure) confirms that you aren't going to be a no-show, and allows you to print your boarding pass. This saves time when you arrive at the counter at the airport. Just enter your name, and either confirmation number or ticket number (whichever is asked for). You will be prompted if there is anything else to enter. Very simple procedure.