There's an exception to this rule: Iodized salt has trace amounts of an additional chemical, Iodine in it. The typical "table salt" in this country has been 'Morton's iodized salt' since the 1920's, though that is changing to some extent.
Iodine is an essential nutrient for thyroid health, and also prevents retardation and goiter. If you eat seafood (from the ocean not freshwater sources) or sea vegetables like seaweed found in nori, you're probably getting enough iodine naturally and don't need to worry about your iodine intake. If you don't, you may need to make sure you use iodized salt to get your daily dose of iodine.
Sodium or potassium Iodide has a slight flavor that professional chefs don't like, but if it's all you've ever know, you probably can't taste the flavor.
Also, one last note, prepared foods, even the ones loaded with salt, generally don't contain iodized salt, so don't count on your intake from that source either.
Hope this helps.

From the wiki article, 'cause hey, the more you know:
The term "kosher salt" derives not from its being made in accordance with the guidelines for kosher foods as written in the Torah (nearly all salt is kosher, including ordinary table salt), but rather due to its use in making meats kosher. 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. "Kosher certified salt" is salt that has been certified as such by an appropriate religious body.[2]

I'm Canadian and have been mildly annoyed by the kosher salt I've brought in the US, because it's large and granular, and not perfect and flaky in the way that I'm used to. The difference in texture throws me off, and I'm still brand shopping for kosher salt that's the way I want.

The biggest difference you'll notice flavor wise is basically what was said in the article. Since kosher salt is, for lack of a better word, fluffier that table salt, it dissolves easily compared to table salt (more surface area.) So if you sprinkle some on french fries, say, most people would say the kosher salt ones taste better because the flakier salt gives you a quicker taste of the salt than table and salt is a flavor enhancer. So you just get the salt a little more rapidly on top your food.

Now if only more baking recipes would specify kosher or table (I was always told you should always assume measurements are off kosher but with everyone under the sun writing cookbooks these days who knows!)

"A tablespoon of kosher salt has salt, by volume, than table salt,..." I think you're missing a modifier in there - you probably meant to say "has LESS salt".

We use Kosher salt almost exclusively, even for preparation, and it works out great.

I used to only buy regular "granular" table salt. In the last couple of years when I started trying sea salt and kosher salt, I found that when I cooked with them my food seemed to come out *way* over-salted, even though I felt like I was using the same quantities/volumes of salt in my cooking. Is it just me, or do those flakier salts have a more concentrated saltiness? I had such bad experiences (ruined a few dishes) that it's made me a lot more wary of using them in my cooking, unless I'm actually following a recipe that specifically calls for them, in specific measurements...

The best salt EVER for a finishing touch is Maldon sea salt flakes from the UK..they are WOW! Incredible!

Most (if not all) chefs I know exclusively use kosher salt for cooking, and then a "nicer" sea salt for finishing. I don't know any chefs who use table salt in their cooking, ever. Only in baking, and even then it's usually fine-grain sea salt.

Thanks readers, very helpful! I had a friend over the other day who specifically requested kosher salt to make Micheladas (the many wonderful uses of salt!) and I was very curious. I use finishing salts but I'd never bought kosher salt before. Now I know :)

A lot of table salt has anti-caking ingredients in it. Also sometimes there is a starch added. Read the labels at the store, it's shocking what they put in salt.

Table salt is "used more for seasoning a dish while still in process."
Jesus this was poorly written. A fantastic combination of ommitted words and just plain false information. Kudos.
The question was the difference between kosher salt and 'regular' sea salt, which is a fine question. You answered her question by first describing the difference between kosher salt and table salt. Then told this person the biggest difference is crystal size. Neglecting to say anything about iodine.

On top of all of this you claim kosher salt is mainly used as a finishing salt. Have you ever cooked anything, ever? It's a serious question.

Actually, not all kosher salts have big, coarse crystals. It varies widely by brand and some are much closer to table salt, density-wise.

#1 to susymac, definitely get some Maldon. It is The Best.

Good question.
Poor response.
Not even CLOSE to accurate.
Google is your friend.

Wow, not only did you answer the question badly and get some of the facts wrong you seem to have completely missed the proof reading stage.

A) The reason table salt is called that is because it's used at the table, it the grain size salt shakers are generally made for. Most has iodine in it but you can find non-iodized table salt as well (my table salt is a sea salt with the usual table salt grain size, I get enough iodine in my diet I don't need it in my salt and I don't like the taste).

B) Kosher salt is pretty much the cooking standard in almost every professional kitchen and many home kitchens. Why? It's easy to measure out, generally doesn't have anti-caking ingredients or been iodized (both of which can affect how recipes taste or their texture), and is incredibly cheap.

C) Sea salt only refers to the source of the salt. It comes from evaporating off sea water without a lot of purifying (whereas typical table salt and kosher salt are almost purely sodium chloride because impurities in the salt have been removed, rock salts are another category entirely). Sea salt can come in many different grain sizes and shapes, the source or evaporation method can also affect the flavor and amount of trace minerals in it. There are sea salts which are delicate beautiful finishing salts and sea salts that are good everyday cooking salts.

I used Kosher salt for everything, including baking, but I'd like to try a flaky sea salt for finishing. Can anyone recommend a good one?

"Jesus this was poorly written. A fantastic combination of ommitted words and just plain false information."

jess13, FYI, "omitted" only has one "m". I usually find it helpful to spell check before chastising somebody for their about their writing.