Concrete sealer is a protective coating applied to concrete surfaces to enhance durability and longevity. It helps prevent water, oil, and other substances from penetrating the concrete, which can lead to damage over time. Sealers can also improve the appearance of concrete by providing a glossy finish or enhancing color. There are different types of concrete sealers, including penetrating sealers and topical sealers. Penetrating sealers soak into the concrete, while topical sealers form a protective layer on the surface. Choosing the right type depends on the specific needs of the project and the environment in which the concrete is located.