Yarn overs are used to increase stitches and/or create holes in the knitting for lace.
I have just knitted two knit stitches and HERE is where the pattern indicates to put the YO.wrap the yarn from behind the work and bring it to the frontbringing it on throughbringing it through to the backthen wrap to the backthats the YO but now the pattern wants us to knit the next stitchhere is how our yarn over looks next to a knitted stitch
When I first started knitting it was hard to find through tutorials that showed visually every step along the way. I will make many more of these in my blog to help with the patterns I provide.