How do I stop a leaky faucet from dripping constantly?

To stop a leaky faucet, first turn off the water supply valves under the sink. Then remove the faucet handle, usually by unscrewing a screw hidden under a decorative cap. Once the handle is off, you'll find either a cartridge, ceramic disc, or rubber washer depending on your faucet type. For older compression faucets, replacing the rubber washer at the bottom of the stem is usually the fix. For cartridge or ball faucets, replacing the entire cartridge or worn O-rings typically solves the problem. Take the old parts to a hardware store to find exact replacements. Reassemble everything, turn the water back on, and test. Most repairs take under an hour and cost just a few dollars.