A monolayer is a single, continuous layer of molecules that is only one molecule thick. These layers can form on surfaces and are often made up of lipids, proteins, or other organic compounds. Monolayers are important in various scientific fields, including materials science and biochemistry, as they can influence the properties of surfaces and interfaces. Monolayers can be created through different methods, such as Langmuir-Blodgett techniques or self-assembly. They are used in applications like drug delivery, sensors, and catalysis, where controlling the surface properties at the molecular level is crucial for enhancing performance and functionality.