When you make some kinds of soup, it is tastier to use meat or vegetible stock instead of just water.
To make this stock, Koreans often use anchovy (멸치) or kelp (다시마). However anchovy is quite expensive and it can be a bit hassle to use (trimming the head, tail and organ etc), so I sometimes use powdered anchovy instead.
This is a picture of the anchovy powder (멸치가루) I use. It is 100% pure anchovy. The price is about 2800 won (US $2.95)