What does it mean by "drop yarn over"

I was reading directions for this scarf www.morehousefarm.com/Original/Pattern/duJour/15/ when I came across the term “drop yarn-over.” How do you do that? :??

Thanks.

When you come to the YO you did on the previous row, slip it off the needle, don’t knit or purl it. It makes an elongated stitch.

sue

Ohhh! Thank you for clearing that up. I love this forum!

Monica