@jmrubillon First off, the phrase "kosher salt" is deceptive. I'm no expert, but I believe that all salt is kosher. It's really kosherING salt; that is, it's the kind of salt that's used in the preparation of kosher meat to draw out all of the blood. It's better for that than table salt because its granules are larger and therefore adhere to the meat better.

The real reason that recipes specify kosher salt it is that it's somewhat less salty by volume than table salt because of the big granules. That is, a teaspoon of kosher salt contains less actual salt than a teaspoon of table salt because the table salt packs tighter because of the small grains. So a recipe that calls for "one tsp. salt" is ambiguous if it doesn't specify what kind of salt. The default assumption is regular table salt, so if the recipe writer used kosher salt when developing the recipe, they need to say so.

You can certainly substitute table salt for kosher salt. The rule of thumb is to use half the amount the recipe calls for.