A limit order is a type of buy or sell operation where the trader sets a specific price that the asset must hit before entering a trade. For a long trade, the limit price is generally lower than the current price. For a short trade, the limit price is generally higher than the current price.

For example, say the current price of ETH is $205, and you believe that ETH will drop down to $200 before shooting back up. So you want to go long on ETH when it hits ETH so you can maximize profit. You also don't want to stare at the chart waiting for it to drop down.

So you create a limit order at a price of $200. The order will remain open until ETH drops to $200 or below, and the fill.

For a long trade, if you set the limit price at or higher than the current price, it will fill immediately, often at the price you set, which could be higher than the current price.