Circular needles are used for seamless knitting, when you need a `tube' like a sock or hat, or for sweaters. You can also use them like straight needles, knitting flat or back and forth on them. I don't use straight needles at all anymore, just the circs for everything.
sue- knitting heretic
The Following User Says Thank You to suzeeq For This Useful Post:
I'm with suzeeq! I use circular needles for everything. Long straight needles just kill me.
Keep in mind that when knitting in the round you may have to switch to double pointed needles (dpn) because the "tube" is too small for your circular needles. If you don't have enough stitches in the tube, then you can't join the stitches on the circular needles.
Circular needles are two needles with a thin cable between them, allowing one to knit "in a circle"....as the others have said. I don't have many of them myself, and the ones I do have keep twisting on me (cheap needles, cable won't lay flat). Eventually, I'll have a nice set of circs, but for now, I've got my straight needles.
alleusion on Ravelry
...I can't have too many projects, I still have empty needles...
And there are ways to somewhat straighten out the cords on circs. Heat them by dipping in hot water or using a hairdryer on them then let cool straight helps. So does using them, the weight of the knitting straightens them and don't store them coiled up.