Double Pointed Needles (DPNs) come in packs of 5 needles.

They are used to knit things in the round that are too small for circular needles, e.g. socks, cuffs, the top of a hat.

They are a great alternative to using Magic Loop on Circular Needles for small diameter knitting.

Another really great option, if you really don't like DPNs is Shorties by Chiaogoo!