Bracket orders are designed to help limit your loss and lock in a profit by "bracketing" an order with two opposite-side orders. This way, you decide both the ceiling and floor prices for squaring off your position while entering a trade.

A bracket order combines three orders in one. 

• An initial order
• A corresponding stop-loss order (2^nd leg) 
• A corresponding profit objective limit order (3^rd leg)

If the stop loss trigger price is hit, the stop loss order gets executed as a market order and the 3rd leg (the profit objective order) automatically gets cancelled. Similarly, if the profit objective trigger price gets hit, the 2^nd leg stop loss automatically gets cancelled. If the condition for the two limit trades is not met by 3:15pm, the order is automatically squared off (unless its manually closed by the trader).
 

For placing a bracket order, you need to specify a trigger price (in ₹ or in %), the limit price, a stop loss price (your floor price) and the target price (your ceiling price). You can also choose to add a trailing stop loss here.

There is also an additional field called “Trailing Stop Loss". When you place a bracket order, you get an option to either place a fixed stop-loss order or also an ability to trail your stop-loss. In Trailing Stop Loss, if the stock or contract moves in your direction by a particular number of ticks, the stop-loss will go up/down based on if you are long or short automatically.