Colored. Pink, black, gray and other colored salts contain minerals or other impurities that give them their hue. The impurities may come from the sea water itself, or from the clay or substrate at the bottom, or they can be deliberately introduced. Hawaiian pink salt, for example, is colored by the iron oxide from clay that is added to the salt.
Iodized. Containing added iodine, a mineral needed for thyroid function. Inadequate consumption of iodine can cause goiter.
Kosher. So-called not because it is kosher (although it is) but because it’s the best kind for kashering, or making kosher: extracting the blood from meat. Its relatively large, flat grains can be left on the surface of meat to extract blood without dissolving.
Rock. The salt of the earth. It can be harvested directly, but it’s usually pumped up in solution and re-evaporated on the surface. This is the salt you use on your driveway and in your ice cream maker, but it can also be refined for table salt.
Pickling. Salt without additives, which can cloud pickling liquid. It is fine-grained enough to dissolve quickly.
Popcorn. Salt made from very fine grains so it is less likely to fall to the bottom of the popcorn bowl. (Butter also helps prevent that problem.)
Sea. Formed through the evaporation of sea water.
Table. Fine-grained salt with additives (usually anti-caking agents) to make it flow smoothly and resist absorbing moisture from the air. It is often iodized.