This crochet stitch might be referred to as moss stitch, or linen stitch.
Using multiple colors of yarn can really show off the way the rows interlock into the rows below, hence my calling it interlocking rows.
I have used this technique for almost every sort of project. It has a little more give than traditional crochet stitches.
It does not matter how many stitches you start with, just make your foundation using my Foundation Single Crochet technique to the length you want, and get started.
Sit down with some practice yarn or your project and watch this tutorial video and work along.
P.S. Here are some photo examples of how this stitch has been used. I’d love to add your version to help inspire other stitchers. When you start your project, don’t forget to create a project in Ravelry! Share the link to your project in the comments of this post, and share on social media using the hashtag #ashleyafghan