Salt is another game day treat
that goes on almost everything. The primary ingredient in each type
is sodium chloride. US requires food-grade salt be a minimum of
97.5% pure.
Table salt usually contains an anti-clumping agent, like calcium
silicate, and also iodine. Kosher salt usually does not contain
either. In the old days, people used to put a few grains of rice in
their salt shaker to keep the salt from clumping.
The main difference between Kosher salt and regular salt is the
grain size, with table salt being much smaller, because Kosher salt
is less processed.
Kosher salt is not called “Kosher” because the salt is certified as
kosher, but because this type of salt was used in the process of
koshering meat to remove surface blood from meat without making the
meat too salty.
Incidentally, iodine was first added to salt commercially in the
United States in 1924 by the Morton Salt Company at the request of
the government, because people weren't getting enough iodine in
their diets. This caused many people to develop goiters or swelling
of the thyroid gland. The practice was taken from the Swiss, who
began adding iodine to salt many years earlier. Today most people
get enough iodine in their diets, but many government health
agencies around the world still recommend adding it to salt.