What is a Good-Till-Date order and can you explain what is smart order routing?

Smart Order Routing:

This is a facility that has been recently introduced in the Indian markets. The trading screen on the HDFC Securities platform gives you the option to execute orders either at the NSE or the BSE, depending on where it is listed. There is also the third option of using smart order routing (SOR) order. If you select SOR order, then the trading engine automatically detects the best price and executes the order. For example in case of a buy order, the SOR will automatically execute at the exchange where the price is lower. In case of sell orders, the SOR will automatically execute the order at the exchange where the price is higher.

Good till Date (GTD) orders:

Most orders that you place on the exchange are by default GTD orders. A GTD order is valid till the end of the trading day. When the trading for the day closes, the order is automatically cancelled. GTD orders become relevant when either your market orders do not get executed due to poor liquidity or your Limit orders do not get executed due to unfavourable price. In both these cases, the GTD order will be held in the system till the end of the trading day.

There is also another kind of an order which is IOC (Immediate or Cancel) order where the order is executed only if it can execute the moment it is placed. Else, the order stands automatically cancelled. This type of order is more popular among institutional investors and large proprietary traders.