Closing costs are the fees and charges due when your home loan officially closes. They cover everything from the lender's processing work to the county's paperwork to your first year of homeowners insurance. Some go to your lender, some to third parties, and some are simply pre-paid expenses that get held in escrow.
The total is usually 2%–5% of the loan amount, but the exact figure varies by location, loan type, and what you negotiate. By federal law, you'll receive a Loan Estimate within 3 days of applying, listing every fee in detail.