M1R (Make 1 Right)
M1R is an increase technique that creates a new stitch by lifting the strand between two stitches and knitting it twisted, so the increase slants right.
Explanation
M1R (make one right) is one of the most common ways to increase invisibly. You lift the strand between stitches from back to front and knit into the front loop, which twists the stitch so the increase slants to the right. Because it is nearly invisible in stockinette, M1R is often paired with M1L to create matched, symmetrical increases on either side of a sleeve or raglan line.