These are Jumper wire male to male, used in connecting female header pin of any development board (like Arduino) to other development board or breadboard. Breadboard can be used to prototype electronic circuits without soldering. It works great for connecting and testing sensors, ICs, or other circuits. The term is commonly used to refer to solder less breadboard. Because the solder less breadboard does not require soldering, it is reusable. This makes it easy to use for creating temporary prototypes and experimenting with circuit design. Older breadboard types did not have this property. A strip board and similar prototyping printed circuit boards, which are used to build permanent soldered prototypes or one-offs, cannot easily be reused. A variety of electronic systems may be prototyped by using breadboards--from small analog and digital circuits to complete central processing units (CPU's).