When it comes to shaping a knitted project, one of the basic techniques you'll need to know is how to add a stitch. An added stitch is called an increase, and there are multiple ways to work knitting increases.
This is probably the most standard increase, this is where you increase by making two stitches out of one. You knit into the stitch as normal first. But after pulling the right-hand needle out, don't slip the stitch off the left-hand needle. Instead, keep that stitch on the needle and now with your right-hand needle knit into the back loop of that stitch. Now you can slip the stitch off the left-hand needle. This way you've increased by one stitch.
Knitting through the back loop.
This is the same idea, but done on the purl side of the work. First purl as normal. Then purl into the back loop. This can be tricky the first couple of times you do it. Just remember you need to keep the yarn bump on that second stitch on the front side of your fabric; so you have to insert your needle into the back loop from left to right, and then wrap your yarn around the front of that stitch on the right-hand needle.
Purling through the back loop.
Note how the needle comes in from the left
of the back loop and winds up in front of
the left-hand needle tip.
For this increase, you pick up the horizontal bar between the stitch you just worked and the next stitch on the left-hand needle. Pick it up with your left-hand needle and then knit it like a regular stitch. You can either pick up that bar by going in from front to back or from back to front. The way you pick it up will dictate which way the stitch slants.
The horizontal bar you will pick up to work a
This is completed simply by wrapping the yarn around the right-hand needle between working two stitches. If you've ever worked with a new knitter who finds herself inadvertently increasing stitches from row to row, I suspect this is the likely culprit. A yarn-over increase is most often used in lace patterns, with a corresponding decrease in the next row. It's not commonly used in other types of patterns for shaping purposes because this type of increase creates a small hole in the fabric.
The yarn over.
This type of increase is used when you need an edge or a break between stitches on one row and the next, for example--working around the thumb hole on a mitten. It can also be a way to add new stitches to the end of a row. To do this increase, you make a loop with the yarn, twist it around, and put it on your needle.
A loop cast-on stitch added to the end of a row.
Now you know how to do five of the most basic stitch knitting increases! A detailed pattern will usually tell you which increase to use. This is because each type of increase creates a slightly different look or a slant to your work. Of course, if you're making your own pattern, you get to decide which kind of increase to use! Check out Stefanie Japel's online Craftsy class Knit Lab to explore more increases in depth! Which increase do you find yourself using most often?