A terminal is the point at which a conductor from an electrical device comes to an end. It is at this point where components connect to external circuits. It can simply be the end of a wire, or fitted with specific connectors, fasteners, adaptors, or lugs.
The connection at a terminal may be temporary, using hardware that can easily be installed or removed. Temporary connections are accomplished with discrete hardware like wire nuts or crimp terminals, which can usually be fixed or removed by hand.
Other more permanent terminals require certain tools or methods to install, like soldering, mechanical, or compression lugs. In a closed system, two terminals are used: a positive terminal and a negative terminal. Current flows positive to negative, closing the circuit to provide a secure connection between equipment.