U-Wrap Knit (UW, U-wrap, UK) This is like doing a half stitch, but in reverse. You take the yarn and put it in front of the peg, and wrap around the back, but not all the way around. Take the existing stitch and knit over the half wrap you just did, while holding the working yarn so it stays in place. This is a tighter knit stitch than the e-wrap.
Plain Knit Stitch: (PK, K, Knit or Reverse Purl) This is done in some patterns when you want a tighter knit stitch. It’s similar to the purl. You put the knitting tool in from bottom to top, grab the working yarn, pull it through, remove the existing loop from the peg, and put the new loop over the peg.
Flat Knit Stitch: (FK, K, Flat Knit) This is the tightest knit stitch and can be difficult to work with on the next row if you’re a very tight knitter. I learned this the hard way. Take the working yarn, put it in front of the peg (loosely) and then knit the bottom stitch (existing stitch) over the working yarn. This creates a tight fabric and is good for socks.