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Kris Robertson/Demand Media

By nature, swimsuits are among the simplest bits of clothing out there; if you retain your dignity at the beach and look good doing it, consider your mission accomplished. Because it toes the line between utility and fashion, swimwear has a hidden layer of complexity: A quality swimsuit should not only look great, it needs durable, stretchable and water-resilient fabric. For both men and women, most suits feature a blend of different fabrics – including natural and synthetic materials – and each brings distinct qualities to the table.

Tried-and-True Nylon

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Kris Robertson/Demand Media

If you pick up a swimsuit off the rack, there's a pretty good chance it contains nylon. This lightweight manufactured fiber offers a lot of stretch and hearty moisture-wicking capability, making for speedy drying times. On the flip side, nylon swimwear may fray or fade after prolonged sun exposure.

Shapely in Spandex

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Kris Robertson/Demand Media

Spandex lends itself to a great deal of modern swimwear, though it's typically not the sole fabric. As part of a material blend, soft and light spandex ups the swimsuit's stretchiness; the more spandex in the suit, the more shape-hugging it is. This makes it a vital component in competitive swimwear. Spandex slims the figure, but chlorine takes a toll on its elasticity over time.

The Poly Alternative

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Kris Robertson/Demand Media

Polyester, not nearly as common in swimwear as its stretchier brethren, looks similar to nylon but is heavier and not very stretchable. Man-man polyester earns high marks for durability, but it's a thirsty fabric, which may weigh down your swim. Modern polybutylene terephthalate, or PBT, reduces absorbency, speeds up drying times and amps up the elasticity.

Classically Cotton

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Kris Robertson/Demand Media

Early swimwear was made of wool or cotton, and the latter fabric can still help you nail the vintage look. While comfortable and retro-chic, cotton swimwear isn't quite as form-fitting as stretchier options, and it doesn't hold up well to chlorine. For a more durable, curve-hugging middle ground, seek a cotton blended with spandex or polyester.

High-Tech Trunks

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Kris Robertson/Demand Media

Modern men's and women's swimwear sometimes packs a twist. Tan-through fabrics feature thousands of tiny holes that allow light penetration but look opaque when worn tight against the skin. On the opposite end of the spectrum, sun-protective fabrics, which cater specifically to fair-skinned folks, children and outdoor enthusiasts, disrupt ultraviolet rays. These materials are ranked by their ultraviolet protection factor on a scale of 15 to 50 or above.