A coupler is a device used to connect two different systems or components, allowing them to work together. In various fields, such as engineering and electronics, couplers facilitate the transfer of energy, signals, or data between devices. For example, in telecommunications, a fiber optic coupler combines or splits light signals for efficient communication. In the context of trains, a coupler is a mechanism that links railway cars together, enabling them to move as a single unit. This connection is crucial for the safe and efficient transport of goods and passengers. Couplers can vary in design, including automatic and manual types, depending on the specific requirements of the railway system.