An RO (Reverse Osmosis) membrane is a semipermeable membrane that is used to purify water via the process of reverse osmosis. It is made up of multiple layers of material, typically including a thin film composite and a support layer, that work together to restrict the passage of contaminants and allow purified water to flow through. RO membranes have microscopic pores that are so small that only water molecules can pass through, while larger molecules like salt, minerals, and other impurities are left behind. This means that RO membranes are highly effective at removing a wide range of contaminants from water, including dissolved solids, heavy metals, bacteria, viruses, and other harmful substances. They are commonly used in a variety of applications where clean, purified water is essential, such as in homes, offices, and industrial settings.