Breadboard are used with Arduino for prototyping. The basic breadboard consists of power rails on the sides and terminal strips separated in the middle by the DIP support.
However, mini breadboards are a bit different as they do not have the power rails on the side.
So to build prototypes with a mini breadboard, you need to give it power somehow. To do so, you can use a wire by connecting one hand of it to the GND pin of your Arduino, and the other hand to any row on your breadboard. Any component connected to that row will be connected to Ground. Same with the 5V pin.
