The Palestrina knot, or Palestrina stitch is a knotted line stitch (so it fits into my category of “knotted” stitches). While you can stitch just one of these, it is much more effective when many are stitched to form a line. As with most stitches, you can vary the distance between the stitches to make your knots stand out separately or touch each other like a string of pearls.
I like to use this in larger weights of thread (relative to the rest of the embroidery) to create lots of texture. I may be odd in that I like to use the stitch for stems, as seen in the featured image from an in-progress curtain shot. In this case it is worked extremely large, with the knots close together — in 2 strands of sock weight knitting yarn, one of green and the other brown, giving the appearance of a bumpy stem, which contrasts with some of the smoother stitches, and works well with the large weave rustic linen it’s stitched on.