This is a textured pattern, made by alternating blocks of knit and purl stitch. You can make the checkerboards as big or small as you want, and as square or rectangular as you want. It's an easy pattern to play about with to get different textures and looks.
Abbreviations: k = knit; p = purl; st = stitch
In our example, we wanted a rectangular patterned checkerboard, each rectangle being 2 stitches x 4 rows. So we cast on a number of stitches divisible by four, plus 2 extra stitches.
Row 1: *k2, p2, repeat from * to last 2st, k2
Row 2: *p2, k2, repeat from * to last 2st, p2
Row 3: as row 1
Row 4: as row 2
Row 5: *p2, k2, repeat from * to last 2st, p2
Row 6: *k2, p2, repeat from * to last 2st, k2
Row 7: as row 5
Row 8: as row 6
Repeat these eight rows for pattern.