Drop beads (DP) are seed beads shaped like a tiny teardrop with the hole at the narrow top end of the bead. Miyuki drop beads measure 3mm x 3.4mm with a hole size of .65mm.  Toho drop beads are 3mm x 3mm.  Both can be used in patterns calling for small drop beads or 'fringe' beads (because they are fabulous at the bottom of beaded fringe).  If your project calls for more than one color, you might want to pay attention to whether a color is made by Miyuki or Toho as the Tohos are slightly smaller.  Both  come packaged 9 grams to a bag or tube and contain approximately 175-180 beads.