Moss stitch, also called linen stitch or granite stitch, makes a flat, close fabric that looks almost woven. It is built from the shortest crochet stitch and single chains, so it lies very flat and does not curl.
The structure
In UK terms the repeat is: double crochet, chain 1, skip 1 stitch. In US terms the same fabric is single crochet, chain 1, skip 1.
On each following row, the short stitches are worked into the ch-1 spaces of the row below, and the chains sit over the stitches. The offset from row to row creates the tidy, brick-like texture.
Why it suits colour
Because each row is short, moss stitch is excellent for stripes and colour changes. Colours mix into a tweedy, speckled effect rather than sharp bands, which is lovely with variegated yarns.
Things to watch
The fabric is denser than most crochet, so it uses more yarn and is warmer. Going up a hook size keeps it soft rather than stiff.