1. The Good Till Triggered (GTT) - These orders are executed (triggered) once the market price of the stock reaches your desired price i.e the price you mentioned in the GTT Order.
2. The validity of the GTT order is one year.
3. GTT order is Delivery order and GTT order can be placed for Equity (Cash) and Derivatives (Future & Options) segment.
How to place the GTT Order -
1. Select the scrip for which you want to place the GTT order, and also select the Buy/Sell action.
2. In the Delivery tab, select the GTT option.
3. Enter the price at which you want to place the order and enter the quantity.
4. The validity of the GTT order will be one year, and the date till order will be valid, will be displayed below in note.
5. When the GTT order is placed, it will be visible in the GTT Orderbook with status as Triggered Pending and once the price is triggered, the status will change to Triggered. 
Below is the screenshot of the GTT Orderbook -
Benefits of GTT Order -
Investors do not need to track market movements continuously once they place a GTT order.
Investors can easily modify their order before it is triggered.