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Alton Brown had some explanation. It had to do with the crystal size and how more random the crystals where in how it draws out more moisture. Removing moisture means removing more blood, hence koshering the meat.
I do find it easier to cook (not bake) with kosher salt as I am able to add the salt in larger amounts but getting less overall salt. And you should definitely use kosher salt when using salt to encrust anything (e.g. salt and pepper on seared steak).
The larger kosher crystals are simply easier to pinch and distribute even over food. There is no blood left in butchered meat. The reddish juices are from oxygenated proteins that contain iron, not blood.
Finer grained salt dissolves more easily which is better for baking and table use. Substituting kosher salt in baking will throw the recipe off though it is used to top pretzels and bagels. Bigger more noticeable crystals are desirable in that application. Salt crust is similar. You won't over-salt the food as the bigger crystals form the crust faster.
Kosher salt is simply a salt that has been inspected (at least the process of making it has been inspected?) by one of the Kosher unions that determine whether a food conforms with Jewish dietary law. For example, there are not supposed to be any particles of brine shrimp in Kosher salt, since that would be contamination by a non-kosher food. The David's brand of kosher salt (my favorite) is also non-iodized, so it tastes less bitter than "normal table salt" -- not everyone can taste that difference, but the taste is mainly why I choose it in soups and stews.
Table salt (both plain and iodized) is also often certified kosher. The term "kosher salt" in culinary use means a larger, coarse grain. It is called kosher salt because it's used to produce kosher meat by helping to remove blood.
Kosher salt is for koshering: drawing blood out of meat after an animal is killed so the blood doesn't contaminate the meat. Fine grain salt, like table salt, would be absorbed by the meat, but the larger grains of kosher salt do not get absorbed.
The label has nothing to do with whether the salt is consistent with Jewish dietary laws. Nearly all salt is "kosher" (consistent with Jewish dietary laws).
Nor does the label have anything to do with whether the salt is iodized or not. Table salt is more likely to contain iodine, but you can buy large grain iodized salt.
Kosher salt is mainly used because it is easy to handle. It is hard to get a pinch of table salt, easy to get a pinch of kosher.
Also, keep in mind that kosher salt is about half as dense as table salt.