Which one should I use: Limit Order or Stop Order?

When it comes to limit orders, your broker will know when to sell or buy a stock at the limited price. Other than this, you will have to get the order filled even at higher prices than you expected when it comes to stop orders.

Why is the Limit order not filled?

If the price of the stock is above the limit price, the order becomes null. This is because the investor wants to invest that particular amount in stock only.

How to cancel stock Order?

You can only cancel the limit order or stop order until it is not filled. You can do that anytime. Usually, the limit order is in waiting until it reaches the required amount. So, if you wish to cancel the limit order, you can do it quickly.