These are male to male breadboard wires. They have machined, rounded pins so that they will fit easily into a breadboard hole without damaging it or permanently stretching it.
I find that I use my wires quite often for a quick prototype of a new component, connecting power and ground to a component to see if it works (reality check test), testing LEDs, and doing a quick wiring of servo motors that have the Futaba 0.100" three-pin connectors.
You'll find that they have many uses in rapid prototyping and my wire set is now indispensable to me.
They come in red, green, blue, white, and black colors. In general, I like to use red and black for power and ground connections, just to conform to standard colors and for easy identification if I'm prototyping more complex circuits.