A coupler is a device used to connect two different components or systems, allowing them to work together. In various fields, such as engineering and transportation, couplers can link pipes, cables, or rail cars. They ensure a secure connection, enabling the transfer of fluids, electricity, or mechanical force. In the context of railways, a coupler connects train cars, allowing them to move as a single unit. This is essential for the operation of trains, as it provides stability and safety during travel. Different types of couplers exist, including knuckle couplers and buffer and chain couplers, each designed for specific applications.