Table salt comes from salt mines. It is fine-grained and usually contains calcium silicate or some other anti-caking agent to help it flow freely. Some table salt also contains iodine. Table salt is 99% sodium chloride.
Kosher salt also comes from salt mines but is coarser-grained. Some brands contain anti-caking additives.
Sea salt is produced when seawater is evaporated. Supposedly there is a subtle difference in taste between salts from diferent areas, and sea salt is often named for the sea from which it is produced. Sea salt contains 95% to 98% sodium chloride and 2% to 5% trace minerals.
Pickling salt has a fine grain like table salt, but it does not contain any of the anti-caking agents or iodine, because these ingredients would make the pickling brine cloudy.
A patch of volunteer poppies at the edge of our meadow