There are many great debates among knitters, including Top-Down vs. Bottom-Up, K2tog* vs. SSK*, English* vs. Continental*, tying knots vs. oh-my-God-I-can't-believe-you-tied-your-yarn-ends-together, and many, many more. But the great debate I'll tackle for today is Straight vs. Circular needles (or, for that matter, Double-Pointed vs. Circular needles).
In case you're very much a beginner knitter, I will describe them for you in confusing terms:
A Straight needle is shaped like a T where the trunk of the T is extremely long and has a point at the end, and the top of the T is larger than the trunk, to prevent stitches from slipping off the other end. They normally come in pairs, like hipsters having a dinner out at Vancouver's Main Street district:
A Double-Pointed needle is shaped like a bamboo skewer, with nothing to prevent stitches from slipping off either end (but they sell little plastic doohickeys to stick on the ends, for nervous knitters like me--especially if your knitting travels in a purse or murse and is jostled). They normally come in groups, like hipsters having brunch in Vancouver's Mount Pleasant district:
A Circular needle is shaped like a great big U where the tips of the U are pointed and rigid for a few inches, and the rest of the U is formed from a flexible cable connecting the pointed rigid bits. The cable can be very long, so you will also see Us with the bottom of the U coiled around several times for easy storage. They normally come in single units, like me grabbing lunch next to the yarn shop so I can read in peace without feeling pressured to clean the garage:
Now, the beginning knitter might feel that Straight needles are used for straight, flat knitting, like scarves, or dishcloths, or bits of sweaters which will eventually have to be seamed together (or else placed lovingly in the drawer, awaiting the day that you meet a unicorn, a will-o'-the-wisp, and someone in your knitting group who loves seaming other people's knitting together).
The beginning knitter will probably also learn that Double-Pointed needles are intended for small circumference knitting-in-the-round projects, like socks, or mittens, or hats for American Girl Dolls owned by children with parents who balk at paying $28 US for the "Casually Cozy Outfit" so that Melody can get a cute 3 inch toque with ear flaps.
And that same beginning knitter will likely imagine that Circular needles are meant for larger knitting-in-the-round projects, like pullover sweaters, hats (at least until they decrease toward the top), and socks for elephants.
But no! Circular needles can be used for EVERYTHING. Seriously. EVERYTHING you would ever want to knit can be knit on a Circular needle, so long as you've cleverly chosen one long enough. Yes, it sounds counter-intuitive--how can you knit a tiny sock on a giant 42 inch Circular needle? But you can! Here's how:
Flat Knitting on Circular Needles
Here's a secret: your needles really only need to be rigid at the points. It would be very difficult to knit with pointy but floppy spaghetti, but so long as the bit near the points is nice and firm, the rest of your needle can be as flexible as all get out. There's the joy of Circular needles--they've made the points rigid, and that's all you need. So go ahead and pretend that one end is a left-hand Straight needle, and the other end is a right-hand Straight needle, and just knit. When you get to the end of the row, turn it around, and keep going.
And it's not like this is in any way inferior to using Straight needles. In fact, there are advantages:
You won't lose one of your needles (unless you lose your entire project).
You can slide your unfinished work down onto the cable part, decreasing exponentially the chances that it will leap off of your knitting in an unguarded moment.
I can think of two reasons, and two reasons only, why you would want to use Straight needles when you could use Circular needles:
You are an old-timey person who knits with the left needle held rigid in your armpit (yes, this is an actual method). This is hard to do with Circular needles.
You are an actor in Outlander or Timeless or Another Period, and your character knits, and you want to be historically accurate.
That's about it for reasons to use Straight needles.
Knitting-in-the-Round on Circular Needles
This is where it gets really exciting. The obvious use for Circular needles is knitting something where the circumference of your knitted item is more-or-less the same size as the circumference of your knitting needles, or slightly larger (it's easier to bunch up a few stitches than to streeeeeeeeetch them out around your Circular needle).
A less obvious use, because it took a few decades for clever knitters to work out, is that you can use Circular needles to knit projects where the circumference of the item is ridiculously smaller than the circumference of the needles. There are three methods.
Use 2 Circular needles (invented by Cat Bordhi). Some people really like this method, but it seems unnecessarily complicated to me, there's a lot of extra flopping aboutness, and you need to buy twice as many needles.
Use 1 Circular needle--the "Magic Loop" method (invented by Sarah Hauschka, who I've met, and she was lovely, and not-at-all superior about having invented such a ubiquitous, clever technique). There are numerous youtube videos, but essentially the idea is that you don't need to stretch your knitting around your large Circular needle, you just need the tips to touch--that's where all the work is done. So you ignore extra cable at the end of your right needle, and you pull extra cable out through any two random stitches in the middle of your work, and carry on knitting until you have to ignore/pull again.
THE EASIEST METHOD: Use 1 Circular needle--the easier "Travelling Loop" method, which means pull your right hand needle as far as it will go and then just start knitting with that and see what happens--it's so easy, and it works.
Here's my insight about these last 2 methods: if you're knitting something where you have enough stitches to comfortable fit overtop of both rigid ends of your needle and then some, then you can use the easier "Travelling Loop" method (e.g. a hat), but, if you're knitting something so tiny that you don't have enough stitches to cover both rigid bits (e.g. a sock), then you must then use the proper "Magic Loop" method, which really involves two loops. Trust me on this!
(And for this reason if you have a choice between small rigid tips and long rigid tips, you will find small rigid tips more useful as they increase your chances of getting away with the Travelling Loop.)
Off the Needles
I have finished my "Random Hat" (which was knit using a Travelling Loop method, at least until the decreases, when it eventually got small enough to use the Magic Loop method. I have coined a general term for using both methods the "Tragic Loop" although this nomenclature is entirely ironic as nothing could be more splendid.
The Random Hat was knit with some scrap yarn, and is Very Easy to knit. it looks narrow, but that's only because of the ribbing--it will expand to fit head-shaped heads.
Here is the pattern.
1. Knit a gauge swatch* in stockinette. (Unlike most gauge swatches, this is for a freakin' hat, so don't waste too much time on it, you just want to get a quick sense of the needle size and yarn combo.
2. Measure the intended head.
3. Cast on the right number of stitches.
"Wait, wait," I hear you cry, "what's the right number of stitches? How will I know?"
Well, gentle reader, if your gauge is, say, 5 stitches per inch, and your intended head is 20 inches around, then you need 100 stitches. It's just math, and it's not hard math. (If your gauge is 3.73 stitches per inch and your head is 21.6 inches, then use a calculator, for Pete's sake!)
4. You actually will be knitting 3 knit, 3 purl, to make a rib (which is why the gauge isn't needed to be absolutely perfect--the rib will cinch it in so it will fit a variety of similar heads) ... so you need to cast on something divisible by 6 to make the pattern work. If you calculated 97, say, then cast on 96.
5. Knit 3, Purl 3, until the hat is almost as long as you like.
6. If you got bored in the middle and had extra yarn in a contrasting colour, feel free to add it in. So long as your stripes don't get too wide, when you switch colours back again, just lift up the old yarn and start knitting again.
7. When it's time to decrease (to round off the top) I did this:
Decrease Round 1: Knit 3, purl 2 together, purl 1 (repeat across round)
Decrease Round 2: Knit 3, purl 2 (repeat across round)
Decrease Round 3: Knit 3, purl 2 together (repeat across round)
Decrease Round 4: Knit 3, purl 1 (repeat across round)
Decrease Round 5: Knit 2, purl 2 together (repeat across round)
Decrease Round 6: Knit 2, purl 1 (repeat across round)
Decrease Round 7: Knit 2 together (repeat across round)
Then I just keep knitting 2 together until left with a handful of stitches (6-7 ish), slip your yarn into a tapestry needle, weave through the final few stitches and tug tight. Done! That's the Random Hat Pattern.
On the Needles
(I will mark with a ! when I have advanced beyond last mention)
GGN Norwegian Ski Sweater (Chart A row 6) !
Vice Versa scarf (double knitting!) almost finished the first set of squares !
Persian Dreams Blanket (row 20 of the second hexagon) !
Feather Duster Lace Shawl (I'm repeating, for the first time, the body section)
A Church Mouse sock (prior to heel)
World's Simplest Mittens (prior to thumb)
A Hitchhiker Scarf (started over a year ago. It's for when I'm needing mobile knitting and every other project is stuck at a complicated point. I will be in the middle forever, I guess)
Simply Ribbed Scarf (again, it's ancient, intended for emergency mobile knitting, and I'm in the middle)
*k2tog = "knit 2 together," a common instruction in patterns. Instead of sticking your right needle through the final stitch on the left needle, stick it through the final two stitches at the same time, knit as if they were 1 thick stitch, and slide both off. This will decrease your stitch count by 1 stitch.
*SSK = "slip slip knit," a common instruction in patterns. Slip the last two stitches to the right needle (pundits have varied opinions on whether to slip knitwise, purlwise, or 1 of each), then stick your left needle through the two stitches on the right needle, and now it looks a lot like if you'd stuck your right needle in your left needle--so go ahead and knit the two together, and voila, again, you've decreased your stitch count by 1 stitch.
(Both methods will decrease by 1 stitch, but their appearance in the final knitted fabric are mirror images of each other, so you tend use one on one side, and the the other on the other side, just to keep things perfect).
*English = the method of knitting where you hold yarn in your right hand and wrap it around your needle, also called "throwing" or "American" knitting.
*Continental = the method of knitting where you hold yarn in your left hand and kind of hook it with the end of your needle, also called "picking."
I'm an English knitter or thrower, which is apparently slower but feels more comfortable to me. Try both methods and see which you prefer!
*gauge swatch = a small bit of knitting intending to see how many stitches per inch you get, so you can do the math right for getting your garments to fit. Not terribly important for dishcloths, somewhat important for hats, very important for vests, twin sets, etc. It is trendy nowadays to knit a matching hat as a gauge swatch for a sweater project, so at least you have something useful to show for it (even though it takes longer) but we have not yet come up with something useful as a gauge swatch FOR a hat, unfortunately!