Plumber's putty is a soft, pliable sealing compound that is used to create watertight seals around faucets, drains, and other plumbing parts. It is commonly used during the installation of sinks, drainpipes, and valves. The putty is rolled into a rope shape and applied around the base of the fixture before it is attached to the surface. Once the fixture is tightened, the excess putty is removed. The putty remains soft for a long time, allowing for easy removal if the fixture needs to be replaced.

The steps to use plumber's putty are as follows:

1. Clean the area where the putty will be applied.
2. Take a small amount of putty and roll it into a rope shape that's long enough to wrap around the fixture.
3. Press the rope of putty around the fixture's base.
4. Press the fixture into place and tighten it as required.
5. Remove any excess putty that oozes out.

Remember to check the compatibility of the plumber's putty with the surface you're working on, as some types of putty can stain certain materials. It's also important to note that plumber's putty should not be used on plastic or marble surfaces, and it's not suitable for use where there's water pressure, such as on the inside of pipes.