Yarn Terminology

Have you ever wondered about all this information on the yarn ball-band that you don't understand? There is quite a lot of information on there, meant to let us as users know as much as possible about the product we are getting - How was it made? What does it contain? What kind of projects is it suitable for? How should we treat it? There is much to learn about the yarn from looking at the tag or reading the description on the website. But sometimes, even after reading it, we still don't fully understand what it means, because some of those terms are unfamiliar to us. Wanna know more about it and learn how to best understand the information? Keep reading!

What is it made of?
Personally, the first thing I look at when buying new yarns is the composition - The materials the yarn was made out of. Is it a pure fiber (100% of one material) or is it a blend (a mixture of several materials)? What is the type of fiber used? The fiber content will tell you a lot about how the yarn will "behave" as well as how it should be looked after once your project is done.
The content information is also important in case of allergies, if your project is a gift for someone with sensitive skin or in case it is an item made for babies.
In case the yarn contains wool in it, it is important to know what type of wool it is. I prefer to stay away from yarns that just state "wool" and not the specific kind, as I feel that's not enough information for me as a crocheter. Different kinds of wool have different characteristics. They look, feel and drape differently. Some are more prone to peeling than others, some must be hand washed only, some begin to shed over time - all very important information to know BEFORE buying. The same applies to plant-based fibers.

How is it made?
This information is sometimes featured on the ball band, and sometimes you'll have to take a closer look at the strand of yarn to figure it out yourself. In any case, it is a key piece of information, which will effect the overall look, shape and drape of your finished project.
This category is divided into two sub-categories:
- The way in which the yarn is spun
- Special processes the yarn went through

• Spinning Methods
  One Strand of spun yarn is called Single-Ply. Yarn which is made out of several single-ply strands spun together is called Multi-Ply. When we come across a yarn which is classified as a 3ply, 4ply or any other number, the number refers to the strands of single-ply used to compose the multi-ply.
  Strands of single- as well as multi-ply yarns can be either S or Z twist yarns. Spun yarn twisted in clock wise direction is called S-twist yarn, because the angle of fibers in it makes the shape of the letter "S". In the same way, spun yarn twisted in anti-clock wise direction is called Z-twist yarn, and the angle of fibers in it makes the shape of the letter "Z".
  Normally, multi-ply yarn, which is made of single-ply strands spun in s-twist, will be spun together in z-twist and vice versa. When the single strands are spun in one direction, and the the final ply is spun in the opposite direction, the yarn has more flexibility. When both are spun in the same direction, the final product is firmer and more sturdy.
  In addition to the direction of spinning, you should also be interested in the twist degree. The degree of twist can be classified in three categories: low, normal and high twist.
  Low twist yarn contains less degree of the twist than standard. It has bulkiness and soft feel and posses less strength than normal twist yarn. It shows less structure and looks coarser. Pilling properties of fabrics made of this yarn are poor.
  Normal twist yarn has a normal twist, which falls within the common spinning norms and specification.
  High twist yarn contains a higher degree of  twist than standard. This yarn will have a rough feel to it. This twist degree increases the clarity of the texture of the fabric and it posses higher strength than normal twist yarn. High twist yarn looks finer and has better pilling properties.
  When the spinning method isn't stated on the ball-band, you can try pulling the end of the yarn strand out and take a closer look at it to see how it is spun.

• Special processes
  Some yarn companies put their yarns through special processes to improve certain qualities or its performance in general.
  The most common process made on yarn is the method of making a wool-yarn superwash. Superwash yarn is wool-yarn which is machine washable. If your yarn is marked as "superwash" you can safely wash it in your washing-machine and it will not felt. Each hair of wool is made up of scales. Felting occurs when these scales bind together. The superwash process prevents the scales from binding. This can be achieved by either removing the scales or coating them with a special material. However, when buying superwash yarn it is important to remember, that although it is safe to use in the machine, you should not wash it on high temperatures, as it can damage the superwash coating and cause the wool to felt.
  Just like wool tend to felt, acrylic tend to form pills. Pills are those hard little balls of tangled fibers on the surface of a fabric that make your clothes look worn. They occurs when friction causes fibers to break away from the yarn structure and clump into little balls. To prevent that, yarn companies sometimes put their acrylic yarn through a process which makes it anti-pilling. Through this process, the fiber is specially formulated to resist pilling over time. Items made with anti-pilling acrylic come out of the laundry looking fresh and new, time after time. 
  One more process you might want to be familiar with refers to cellulose yarn, and it is called Mercerisation. This is a finishing treatment, mainly used on cotton and flax, which improves dye uptake and tear strength, reduces fabric shrinkage, and imparts a silk-like luster. It is important to remember, however, that while this process produces a more luxurious type of cotton yarn, it also makes it less absorbent.

Color and dye lot
The color of the yarn will normally be stated as a color number or colorway name, and in some case both. Colorway names can vary from a simple name to something very creative. Want an example to just how crazy and strange colorway names can get? Just have a look at some of the indie yarn dyers on Etsy or Instagram. I always have a good laugh when checking out the names, and I must admit that more than once I purchased a yarn just because of its colorway name.
When yarn is dyed, whether it is in an industrial mill or by hand, it is done so in batches or ‘lots’. Each of these lots is assigned a designated number called the Dye Lot. Each time a color is dyed, the results may vary, which is why dye lots are important. When making one project using more than one skein of the same color yarn, it’s definitely worth checking and making sure all your skeins were colored together in the same dye lot. This is the safest way to avoid inconsistency between balls and ensure a cohesive look to your project.

Yarn weight
The term 'Yarn Weight' (or 'Weight Category') refers to the thickness of the yarn. The thickness of the yarn has a large impact on the overall look of the finished project, as well as the amount of yarn (or balls of yarn) needed to complete it. Yarn weight is divided into categories, each commonly marked with a number and sometimes a name.
Not all yarn companies specify the yarn weight on the ball band, and those who do don't always use the same measurements as others. And just to make things even MORE complicated, there are no universal terms for yarn weights and there is variation within the same weight classes, sometimes even in yarns made by the same company. However, there's a way to figure out the yarn weight or at least to compare it to other yarns and get a better idea about it. This method is called 'Wrap Per Inch' or in short - WPI.
To measure yarn in wraps per inch you need a ruler, and something to wrap the yarn around that has a consistent circumference, like a pencil. Begin by wrapping your yarn around the pencil for a few inches. The yarn should be snug, and the wraps should lay side by side without any over lapping, or large gaps between strands. Make sure not to pull the yarn too tightly to avoid messing up the measurements. Once the yarn is wrapped, use the ruler to measure how many wraps are in an inch. You might want to measure a few places, just as you would a gauge swatch. Now, use the chart in the picture below to compare your WPI number to the weight category and determine the weight of the yarn.

As mentioned earlier, the nature of different fibers and the variation in yarn construction and manufacturing across the globe means that it’s hard to create one universal standard for weight categories. Therefore, it is safer to compare the yarns you wish to use with the WPI method rather than trust the ball band, especially if they were produced by different yarn companies or bought at different times.

Recommended Hook / Needle Size
Most ball bands will state the recommended hook or needle size to use with the yarn. However, I often find that the hook or needle you use depends more on your own style and tension while working with the yarn. I very often end up using a smaller or larger size than recommended and find myself wondering what determines the recommendation on the ball band...
Nevertheless, it can sometimes be useful as a mean of comparison between similar yarns and also give some guidance to beginners or less experienced crocheters and knitters.
When talking about hook and needle sizes we should always remember that different places in the world refer to sizes differently, and the same size hook might be given a different name in another country, which might be confusing. For example, a US size 7 hook is actually a 4.5mm hook. If you tell a European they need a size 7, their minds directly goes to 7mm. See how that can be a problem? To overcome this problem, I give you this size conversion chat, which will help you in case your ball band states a size different than the one used in your country.

Gauge / Tension (Or in other words - Swatching)
Most balls bands will have a tension guide on them. However, it will most likely be geared towards knitters. The tension guide will give you the number of stitches and rows you can achieve in a 10cm (or 4 inches) square of stockinette stitch using their recommended needles.
If you aren't a knitter, most chances are the tension guide on the ball band will not give you any useful information. However, it can be used as a tool to compare yarns and serve as a marker to what kind of crochet tension you can expect. It mainly helps if you have made swatches in the past before working on a project.
If you are an experienced crocheter, you know by now what hook size you use for what yarn weight in order to get the best results in YOUR work tension. If you're a beginner, I highly recommend going through the process of creating gauge swatches in different yarn weights using the single crochet stitch and figure out your tension. When using a written crochet pattern, the gauge needed for the project will often be stated right at the beginning so you can check yourself and make sure you're using the right yarn and the right hook size.
If you are like me - hate swatching and the word "gauge" gives you a headache - then I suggest to completely ignore the tension guide on the ball band altogether...

Care instruction
As a rule, I hand wash all my knit and crochet items and lay them flat to dry regardless of what yarn they are made of. I just think it is the safest way not to damage them. However, this isn't always needed, and so it is useful to know what is allowed or not allowed in terms of washing, drying and ironing.
Most yarn companies use the same care instructions symbols used by the textile industry world wide, which makes it very easy to read and understand, while others might give a short written description of how to care for your finished items.
The care instructions will let you know exactly whether or not you should hand wash, tumble dry, spin, iron or bleach your knitted or crochet items. Honestly, I don't know why someone might bleach anything of this sort, but I guess there are some people who need this specific information told to them...
In case you don't already have one, here is a chart of care instruction symbols for your use:

Center Pull
A center-pull ball of yarn lets you pull yarn from the center rather than the outside. As for me, I love a center pull. I pull my yarn from the center even when there isn't a clear, marked center pull.
Some yarn brands mark the side where the center pull should be on, in case you prefer that method. There are even some companies that stick both yarn ends to the label, with clear marks as to which one is the center- and which one is the outer-pull.
Generally, almost every skein can be made into a center pull or used as a center pull. However, not all of them should be (or made to be), and if you try to pull a non center-pull skein from the center you might end up with a massive case of yarn-barf...
But I do appreciate companies such as Red Heart and Hobbii, who cater to us center-pull lovers by inserting a mark on the ball band.

Red Heart Yarns Label with a marked center-pull

Amounts
Finally, after going through all the information, once we decided this is the yarn we want, it is time for us to determine how much of it do we need? The ball band will typically state the "dry weight" of your skein in grams, ounces and sometimes both. But that information alone doesn't suffice. In order to be able to calculate how many skeins you need for your project, you'll also need to have the yardage (or length) of the yarn. Once again, most companies state the length in meters, yards or both.
If you have a particular project in mind for your yarn, knowing how much you get with each skein is very helpful. This way you won't end up playing a game of "yarn chicken", and you can be certain you have enough to complete your work. Some companies even go the extra mile and specify how many skeins are needed for a specific project on the ball band. However, you should always keep in mind that this information, much like the tension guide, is typically geared towards knitters. Since crochet stitches use more yarn than knit stitches, a crochet project done with that particular yarn will most likely use more than stated on the ball band.
Generally, I always recommend buying one more skein than you think you need, just in case. When it comes to yarn, it is better to have more than you need than not enough...
To make it easier to calculate, here's another "cheat sheet" for you to use. The amounts in this charts have been rounded up to cover both knit AND crochet. Much friendlier than most ball bands!

With all this information in your hands, I hope it serves you and helps you shop for yarn more efficiently both in stores and online. In the future, I hope you take a better look at the ball bands, now that you know how much useful and valuable information is specified on them.