Plumbing grease, also known as plumber's grease or faucet grease, is a waterproof lubricant used in various plumbing applications to ensure smooth operation and longevity of plumbing fixtures. It is typically made from silicone or a similar synthetic compound, which makes it resistant to water and temperature variations. 
The primary use of plumbing grease is to lubricate rubber or plastic parts in plumbing fixtures, such as O-rings, gaskets, and seals. This lubrication helps prevent these components from drying out, cracking, or becoming brittle, which can lead to leaks or malfunctions. By maintaining the integrity of these seals, plumbing grease helps ensure a watertight fit and prolongs the life of the fixture.
Plumbing grease is also used to lubricate the moving parts of faucets and valves, such as the stems and cartridges. This reduces friction and wear, allowing for smoother operation and easier turning of handles. It can also help prevent squeaking or sticking, which can occur over time due to mineral deposits or corrosion.
Additionally, plumbing grease is used during the installation of plumbing fixtures to make the assembly process easier. It can be applied to threads and joints to facilitate a tighter seal and prevent leaks. It is also used in the maintenance of showerheads, aerators, and other fixtures to ensure they function properly and efficiently.
Overall, plumbing grease is an essential tool for both professional plumbers and DIY enthusiasts, as it helps maintain the functionality and efficiency of plumbing systems, reduces the need for repairs, and extends the lifespan of fixtures.