What is The Ephod?

What is The Ephod?
The Ephod(or Efod) is a holy garment that was made for Aaron(Exodus 28:2-3)and his sons(Exodus 28:4); however, Samuel(1 Samuel 2:18) and David(2 Sam. 6:14) both wear one as well. This is rather peculiar as these two are not of Aaron. The ephod, along with "a breastplate, ... and a robe, and a broidered coat, a mitre(the hat worn in the image), and a girdle(the belt around his waist)..." (Exodus 28:4 KJV) create the Priest's outfit. The ephod is specifically described as, "And they shall make the ephod of gold, of blue, and of purple, of scarlet, and fine twined linen, with cunning work," (Exodus 28:6 KJV).