This can be used for borders and thicker lines. You can also vary the spacing of these quite a bit. :D
This is often used to "edge" materials - things like blankets, towels, hems on clothing, etc.
How to do the blanket stitch:
insert the needle where you'll want the bottom of the blanket stitch to be and pull it up through the fabric.
reinsert the needle up and right of your current position. Where you insert it will depend on how tall and far apart you want the stitches to be.
have the needle reemerge so that it lines up with where you put the needle through the last time.
make sure the floss between the fabric and thread is under the needle.
pull the floss through!
to end, simply take the needle down right next to the curve of the last stitch. This will secure the stitch.
Make sure to knot on the backside. You can separate the floss into equal parts and knot it normally, if you like!
See the pictures for extra help. :)
For more stitches, see here:https://www.instructables.com/id/How-to-Sew./https://www.instructables.com/id/Embroidery-101/