Kosher salt or Koshering salt is a term that describes one of the most commonly used varieties of edible salt in commercial kitchens today. Kosher salt has a much larger grain size than regular table salt, and a more open granular structure. Like common table salt, kosher salt consists of the chemical compound sodium chloride. Unlike common table salt, Kosher salt typically contains no additives (for example, iodine), although kosher salt produced by Morton contains sodium ferrocyanide as a free-flow agent. The term kosher salt is restricted to North America.
I'm not a big fan of salt, I dont know why, but the grain is much larger and as the paragraph above explains, no addititves.