Shannon Loitz gives her mother, Cheryl, a taste from the Bonneville Salt Flats in Utah. See more salt pictures.

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Salt is salt, right? When you go to the grocery store to replenish your supply, you probably expect to see just a few varieties, like iodized salt (what most of us use as "table salt") and kosher salt (a coarse salt popular with chefs). But you might also find things like "sel gris" and "fleur de sel." Some gourmets claim that these salts taste different from iodized salt and give additional flavor to foods seasoned with them.

Even if you try not to use much salt, it's almost impossible to avoid it. There are five tastes that all people are able to experience -- bitter, sweet, sour, salty and umami (meaning "delicious and savory taste" in Japanese). Only "salty" is directly related to a substance that we need to consume in order for our bodies to function correctly. Because of this need, humans and animals have a built-in taste for salt.

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All salt contains two basic elements: sodium and chlorine. Sodium (chemical symbol Na) is a silvery-white metal that reacts violently when mixed with water and oxidizes in air. Chlorine (chemical symbol Cl) is greenish-yellow and exists as a gas at room temperature. Because both elements are so volatile, they're found in nature as part of compounds like sodium chloride (NaCl), which forms the mineral halite. Sodium chloride is about 60 percent chlorine and 40 percent sodium [source: Salt Institute]. Although sodium is volatile and chlorine is toxic, together as sodium chloride they're integral to life. Sodium chloride molecules are cubical. The large chloride ions are closely packed together, with smaller sodium ions filling in the spaces between them.

Not only do we need to consume salt, we also need it for a variety of nonfood uses. But if it's so important, why do health organizations recommend that we closely watch our intake? Apparently, there can be too much of a good thing. In this article, we'll examine exactly how salt works in the human body. We'll look at how much salt is too much and what happens when we overload on it or get too little of it. We'll also take a closer look at the many varieties of salt and how it's mined. Finally, we'll look at salt's place in history.

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