It's been 30 minutes and the order has not yet been filled. So I canceled the order.
How long does it take for an order to be filled?
If you want you order to be filled immediately, you can change the 'limit order' to 'market order'.
If you want your order to be filled at a specific price, you can use the limit order. If you buy, the market price must be lower than the order price before your order would be filled. If you sell, the market price have to get higher than the order price before your order would be filled.
If you want your limit order to be filled immediately, you will buy at higher price to the market price, and sell at lower price to the market order.
...assume you are trying to purchase bitcoin and you placed your order at $25200, and bitcoin price dropped to $25190, your order won't be filled till bitcoin bounces back to $25200 or above.
Bitcoin at $25190 and you buy bitcoin at $25200. That is a higher price, which means the order would be filled immediately because you are buying at a higher price. People are selling at higher price and not selling at lower price.