Some is used for all-purpose cooking, others as fancy condiments to finish a dish. Trace amounts of iodine are often added to prevent goiter. Larger, coarser salt used to make meat kosher according to Jewish dietary laws. Kosher salt produced in the Alberger process is hollow, quick-dissolving, and has a clear, mild salt flavor. Use in general cooking in a slightly greater amount than called for in the recipe.
Sea salt comes in many levels of processing.
Granulated sea salt is basically table salt. For general cooking, coarse, less refined sea salt has nice large grains that burst in the mouth with a full briny flavor. Some brands can be rather moist and should be stored in a salt cellar. Use less than the amount called for in the recipe. They are used to add special flavor or texture as a condiment to a cooked dish.