Stop and limit orders are generally referred to ‘basic order types‘ and are commonly used for forex trades. You may also occasionally see them referred to as ‘pending orders‘. Pending orders are placed by traders who intend to purchase or sell when the price reaches a level deemed appropriate (i.e. profitable and worth acting upon). Buy limit orders are placed when you think the price will reach a certain level and then reverse direction.
Buy stop orders are placed when you think a price will reach a specific point and keep rising or falling in that direction. Meanwhile, the sell stop orders and sell limit orders essentially follow the same logic, just that the direction of price movement is the opposite.