So, what is kosher salt exactly. . . I mean, why is it called KOSHER salt?
Koshering salt, usually referred to as kosher salt in the US, is a variety of edible salt with a much larger grain size than some common table salt. Like common table salt, kosher salt consists of the chemical compound sodium chloride.
Unlike some common table salt, kosher salt typically contains no additives such as iodine, although some brands will include anti-clumping agents in small amounts. Additive-free nonkosher salt is also readily available.
The term "kosher salt" comes from its use in making meats kosher by removing surface blood, not from its being made in accordance with the guidelines for kosher foods as written in the Torah, as nearly all salt is kosher, including ordinary table salt. One salt manufacturer considers the term ambiguous, and distinguishes between "kosher certified salt" and "koshering salt": "koshering salt" has the "small, flake-like form" useful in treating meat, whereas "kosher certified salt" is salt that has been certified as such by an appropriate religious body.
Also, as you probably know from experience -- it dissolves easily and provides flavor without oversalting.