Breadboards are used to wire up electrical circuits temporarily. This is often for short term solutions or during the prototyping phase of developing an electrical product or component.
Once a product has been designed usually a printed circuit board will be manufactured and parts will be soldered on to form permanent circuits.
Breadboards have internal connections that enable us to join electrical components into circuits easily.
Most breadboards have ground and power rails on either side of the board that run the entire length.
Power rails (+) are normally connected to either the 5V or 3.3V pins of the arduino.
Ground rails (-) are usually connected to one of the GND pins of the arduino.
The middle pins are connected in terminal strips that are perpendicular to the ground and power rails. They are usually used to make circuits for each component.