Buy the best butter you can afford to create ghee. Ideally it should be organic, but at the very least make sure your butter is from grass fed sources. Butter from grass fed sources has significantly higher levels of vitamins and minerals. The butter should be unsalted, unless you want salted ghee. Ghee has many applications, including sauteing spice bases for curry and shallow frying. Ghee will keep indefinitely but is best stored in the fridge, particularly in hot weather.