What does red wire black wire and brown wire denote?

In electrical wiring, the color of the wires typically indicates their function. The black wire is commonly used as a hot wire, carrying live electrical current, while the red wire may also serve as a secondary hot wire or for specific applications like three-way switches. The brown wire is often used in some electrical systems as a hot wire, especially in European standards. It's important to consult local wiring codes and standards, as color conventions can vary by region.