Melt butter over low heat and let it go until the liquids & solids separate. You'll see a raft at the top, clear liquid in the middle and some solids will sink to the bottom. Skim off the top raft and strain into a container. Keeps in the fridge for a very long time (can also keep at room temp but there is a shelf life associated with that).
Great summation Sarah. The basic thing is just skimming off the solids.