Sweeping changes to the real estate industry are going into effect this week, five months after the National Association of Realtors agreed to a landmark settlement over the way agents are paid commissions.

On Aug. 17, real estate agents across the country must begin following new practices that will require buyers to sign a form before an agent can show them a home, and may radically lower the commission they ask sellers to pay during a home sale.

For years, the standard commission has been 5 to 6 percent, shouldered by home sellers and then split between real estate agents for the seller and the buyer. That fee, while technically negotiable, was at the heart of a lawsuit brought against N.A.R. by a group of home sellers in Missouri, who said the fee was inflated. The home sellers argued that N.A.R., and brokerages who required their agents to be members of N.A.R., had violated antitrust laws by mandating that the seller’s agent make an offer of payment to the buyer’s agent, and setting rules that led to an industrywide standard commission.

Those rules are gone.

Agents will no longer be allowed to make offers of commissions on the online databases used to buy and sell homes, called Multiple Listing Services, severing access to the backdoor channel agents have long used to communicate payments. So what do the changes mean for you? Here’s what to expect.

What do I need to know if I’m buying a home?

Home buyers will now need to sign a written agreement with an agent before they tour a home. These agreements, meant to stipulate exactly how much a buyer is expected to pay to their agent, are required by the settlement, and are not entirely new — 18 states already required them before N.A.R. lost in court.