If you're a newer knitter, sometimes getting the yarn on the needles can feel like the hardest part. It shouldn't be.
We LOVE this method, called everything from "thumb cast-on" to "single cast-on" to "e-loop cast-on" to "backward loop" to "wrap." Whatever you call it, it's easy and super versatile. Win!
How to make the thumb cast-on
Make a slip knot and place it on your right-hand needle. Leave just enough of a tail to weave in later; this isn’t one of those cast-ons that requires a long tail.
Grab the working yarn (not the yarn tail) with your right hand, and hold the needle in your left hand. Wrap the yarn around your thumb from front to back and grasp the ball end of the yarn with your right-hand fingers.
Flip your right hand over to create a loop around your index finger. (See how the yarn wrapped around your fingers looks a little like a lowercase e? That's where the name "e-loop" comes from!)
Then slide your needle into the loop you just created.
Drop the loop from your hand. The loop will now be around your needle, as shown above.
Pull taut to tighten the stitch. The tension here is very important. If you pull too tightly, you'll have a tough time knitting into the cast-on stitches when you start your first row. If you don’t pull tight enough, you’ll have a loose, floppy first row. You may have to test the cast-on a few times to get the tension just right.
Another grip option for the thumb cast-on
If you can't get the hang of the grip shown above, Here's another option that puts your thumb in charge.
Grip the working yarn in your fist, with your thumb pointing up. Wrap the working yarn around your thumb, as shown above...
Then slide the needle into the loop, right along the left side of your thumb.
Drop your thumb from the loop and pull taut.
When to use this cast-on method
If you're just starting out, don't overthink it! This could be the only cast-on you need. For more experienced knitters, know that this cast-on will give you a loose, thin edging on your work, so it’s not recommended if you need a super-stable edge. It's great, however, for certain types of lace work that benefit from a looser edge. A lot of knitters also prefer the thumb cast-on when they have to cast on in the middle of a project, and only need to add a couple stitches to the beginning or end of a row.