The great thing about knitting is that by using two basic stitches, which are the knit stitch and the purl stitch, you can create a wide array of designs. I've covered some other designs in my article, Variations in Knit Stitches but those are only some basic ideas and certainly not the limit of what one can do in the realm of knitting.
The seed stitch is a simple design that only requires your knowledge to do the above mentioned stitches: knit and purl. To create the seed stitch, you will first begin with the knit or purl stitch. It really doesn't matter which one you start with. Now you'll alternate with the other stitch, and then back to the first. Here's an example:
Row 1: knit 1, purl 1, knit 1, purl 1
By the way, a knitting pattern would read the above like this: R1: k1, p1, k1, p1
When you begin the second row, you're going to begin that with the same type of stitch you ended the previous row with. This is very important. If you do not, then you might end up with a rib knit. By beginning the row with the same stitch you ended the previous row with, you will be creating a checkerboard type pattern with the knit and purl stitches. That is basically all the seed stitch is: a tiny checkerboard of single knit and purl stitches.
So for example, if your first row looks like the above, then Row 2 will look like this:
See how it looks exactly like the first row? That's it - that's the pattern! Because the piece you are knitting is flipped around when you knit the next row, it creates a reverse-stitch effect.
So, what good is the seed stitch for? I've seen it used on sweaters, caps, dish towels, afghans - basically, anything you can think of that can be knitted looks great with the seed stitch. Unlike ribbing, it does not have as much "stretch" to it as a rib knit might have. It is a decorative stitch that lays flat and looks wonderful. Try alternating it with some other stitches to make a scarf or afghan all your own!
Click on the image below to view the video tutorial on knitting the Seed Stitch: