How do market orders and limit orders differ?

A limit order specifies the price at which you want to buy or sell; it is executed only at that price or a better one, but it may not be executed at all.

A market order does not specify a price and is executed immediately at the best price available at that moment; it is more likely to be executed, but when prices are moving fast it may be filled at a price quite different from the last price. Which one to choose depends on whether you prioritize certainty of execution or control over the price.