Earnest money is a deposit attached to an offer to purchase real estate. Providing an earnest money deposit shows the seller that your offer is genuine. Not all offers need to have earnest money.
If the offer is accepted, the earnest money is kept by the seller and subtracted from the purchase price. If the offer is rejected, the earnest money is usually returned. If the buyer retracts the offer, the earnest money is usually forfeited.