Perhaps it is intuitive, but I know I was intimidated by swifts at first. They looked like crazy twiggy umbrellas I could surely live without. Isn't that the beauty of knitting...you don't need a lot of gadgets to get the job done? Well, that's true, but I would say a swift is an exception. It is a very useful contraption. (You could throw in a ball winder, too, but it isn't essential.)
The fist step is recognizing the different ways in which you can acquire your yarn. If you shop exclusively at larger craft/hobby stores for your yarn, you have probably only come across what are referred to as balls or skeins of yarn. A ball of yarn is exactly what it sounds like, the kitten's dream, a spherical conglomerate of fiber. A skein is very similar but is more oblong in shape. Often you can pull your yarn from either the inside or the outside of the ball or skein. The first picture is an example of skeins of yarn. You can safely avoid all swifts if you only purchase skeins.
However, as you explore further into your yarn options, it is inevitable that you will come across a hank of yarn. (This terminology is important when you are ordering yarn online, as well.) Higher-end yarns and hand spun or dyed yarn often come in these loose loops of yarn twisted back on themselves (see second photo). It is for the hank that the swift exists. You cannot use a hank of yarn without first winding it into some sort of ball...trust me, if you try you will be very sad with the tangled mess you have left of your beautiful yarn. Often, a local yarn shop will offer to wind a hank for you, conveniently while you shop for more yarn. Sadly, if you do not have a local yarn shop (mine just closed, the next closest is two hours away) you may be ordering online and need to wind things on your own. Now, if you have a hank and no swift, never fear, you simply need a friend (or perhaps a chair back) to hold your loop of yarn while you wind it by hand. It takes a little more time, can be a little more difficult, and you would certainly owe your friend a coffee, but it can be done.
Swifts can be shaped a little differently, made of wood or metal, and be different sizes, but their function is all the same. They are a simple contraption that if properly cared for will last a lifetime. (So don't be scared by the price tags, if used properly, you will only ever need one.) Always read through the instructions that come with any purchase, but I will run through the steps of using a simple wooden umbrella swift.
The bottom of a swift has a c-clamp or something similar which can be used to secure it to a table top. Keep the swift in its collapsed position while securing it to a surface. Also, beware the bevelled edge. My only space to set up a swift is the dining room table, which has a bevelled edge. On my first swift outing, I thought my swift was secure, but the motion of the winding in conjunction with the edge of my table led to a swift plummeting to the floor and breaking. Luckily I was able to fix my brand new swift with some wood glue and tape, but now I place a book in the clamp to flatten the edge and help secure my swift to the table. (Make sure you periodically check to make sure your swift is secure throughout the process.)
Next, you will need to untwist your hank. Find the end that has two separate "legs" and gently pull the hank. It should untwist into a long loop of yarn easily. If it is not doing anything easily, you are likely pulling on the wrong end. Then, look for a clearly defined loop so you can pull the hank into its appropriate circle. You do not want to do this arbitrarily or the tangled mess will quickly follow. I have included a photo of the "clearly defined loop."
You can open your swift a little before putting your circular loop loosely around the wooden slats. Then, after loosely running your circular loop around the center of the swift (where the slats cross each other in an x-like fashion) continue to open your swift until you can let go of your yarn without it falling. It should run in a loop around the middle of your swift. You should only open your swift until you feel a gentle pressure holding your yarn, you do not need to try and stretch your loop as wide as it will go. As long as it is holding the yarn up, you are golden.
Next, you will need to find where the ends of your yarn loop are connected. Often they are tied together and need to be untied, but this makes them easy to find. You only want to work with one loose end, so once you find the ends and untie them, tuck the end of the unused tail behind the hank so it does not dangle. Which end should you choose as your active end? Well, on some hanks it is obvious that one end runs more "in front" of your loop of yarn and the other is a little more "behind," choose the one with least resistance, always go with the front. However, sometimes there is not an obvious end to choose. Choose whichever end, it'll be okay. Some hanks also have ties in other places to keep everything tidy. These are just scrap pieces of yarn and should be removed before winding. I try to avoid using scissors, if possible, untie these scraps with your fingers. Sometimes its hard to tell the difference between tidy little scraps and your actual ends, but since they all have to be untied, it's a moot point, you'll figure it out in the end.
Now you're ready to wind your yarn! You can wind it by hand or with a ball winder. I use a hand cranked ball winder, but if you are doing it by hand, just pick up your starting end and begin winding. The swift will hold your yarn and spin as you pull. There should be a little tension between the ball being wound and the swift, but if you feel resistance or your swift stops spinning, you should stop and investigate. Sometimes the yarn will get a little trapped in a loop and you just need to separate the hank a little bit on the swift before you continue.
As you get toward the end of your hank, be mindful of that little tail you tucked away. It can come loose and get tangled around your swift, creating a little bit of a mess.
Voila! You now have a very usable ball of yarn that should stay tangle free. Yay!