Earnest money is a good-faith deposit you make when your offer on a house is accepted — proof to the seller that you're serious enough to put real cash on the line. It typically runs 1–3% of the purchase price, though competitive markets can push it higher.
The money doesn't go to the seller directly. It sits in an escrow account held by a neutral third party until closing, when it's credited toward your down payment and closing costs. So it's not an extra fee — it's an early piece of money you were going to pay anyway.
The catch: if you back out of the deal for a reason your contract doesn't cover, the seller can keep it. That's why contingencies matter. A financing contingency protects you if your loan falls through, and an inspection contingency lets you walk away after a bad home inspection with your deposit intact.
Read the contingency section of your purchase agreement carefully before you sign — it's the fine print that decides whether that check comes back to you.