The term "Seed Bead" is a relatively non-specific term that refers to any small bead.  They have a rounded shape which could be likened to that of a seed, hence the name "Seed Beads."  Although they are manufactured in many countries, those of Japan and the Czech Republic are generally regarded to be of the highest quality. 

Seed Beads have a vast array of uses which include but are not limited to: loomwork, stringing, embroidery, macrame, fiber arts, jewelry, crazy quilts, crochet, spacer beads, beadwork stitches and various other projects.  Smaller beads necessitate the use of a smaller needle, which in turn can provide an incredibly fulfilling challenge in beading.