Before revision: Bare copper wire is useful when merging a number of connections to form an electrical bus such as the circuit's ground, and when there is enough space to properly route connections, instead of wiring them rats-nest style.
After revision: Bare copper wire is useful when merging a number of connections to form an electrical bus such as the circuit's ground, and when there is enough space to properly route connections, instead of wiring them rat's-nest style.