Uses: The blind hem is a way to hem a garment without leaving a big ol' topstitch line.
Step 1: Finish the edge of your garment by serging or using a zig-zag stitch. Fold the edge under the desired length.
Step 2: Here's the tricky part. Fold the folded edge under towards the right side. Leave the finished edge sticking out from under the fold.
Step 5: Sew down the middle of the second fold you made. The straight stitches should fall along the side with the finished edge, while the ticks to the left should barely catch along the folded edge. Be careful: sew too close to the folded edge and your seam will not open properly; sew too far and you will not catch the folded edge. This also takes practice.
Step 6: Turning the fabric to the right side, unfold the second fold you have made. You should only see the little tick marks on the rights side. If you used a matching thread, even these shouldn't be visible.
Check out the tutorial at Burda Style.