In menswear, few things are hated as much as synthetics. Every time the topic comes up, someone always says how they’ll happily wear a synthetic, sweat-wicking shirt for workouts, but will shun non-natural fibers in other clothing. They know it’s irrational — synthetic fibers are obviously good for some things — but they just assume man-made fibers are a mark of poor quality.

But what are synthetics and what are they good for? In the world of artificial fibers, different materials are often used for different purposes. In fact, even if you’re a staunch natural-fiber partisan, you definitely have some synthetics in your closet. If not your outerwear (e.g. nylon raincoats, wind resistant shells, and parkas), then at least your underwear. Socks, boxers, and briefs all benefit from having a bit of stretch fiber in order to ensure they retain their shape and stay on your body.

So, here’s a rundown of the five most common synthetic fibers you’ll encounter. We cover the pros and cons of each, and end with a bit of common sense on how to judge quality in clothing.

Rayon

Of all synthetics, rayon should be the least controversial. In fact, some people don’t even consider it a true synthetic because it’s made from plant matter, but it goes through so many chemical processes, it’s often listed as artificial.

If you’re not familiar with the term rayon, you’ve definitely worn it. It’s the umbrella term for cupro, viscose, and modal. You may have also seen it in its trademarked form: Lyocell, Tencel, or, most famously, Bemberg. Those are trade names for different types of rayon, just like Kleenex is a trademarked name for a type of facial tissue.

Rayon is commonly used for linings, including those put into suits, sport coats, and tailored trousers. It’s a smooth, silky material that allows you to slide in and out of your garments easily. And it allows things such as jackets to not catch on your cotton shirts, so that the garment hangs properly. The material is so good that tailors switched out their silk linings for rayon ones generations ago. Silk linings don’t breathe well; they’re relatively delicate and expensive. Rayon, on the other hand, is affordable, doesn’t hold odors easily, and wears cool. This is why you’ll sometimes see it used for pajamas. Rayon has been favored as an alternative to silk for many cases since at least the 1920s.

When You Want Rayon: When you want the smoothness and drape of silk, but also want something that’s affordable, doesn’t hold odors easily, and wears cooler.

When You Don’t Want Rayon: Rayon can be a bit high-maintenance. Like silk, it typically requires hand-washing or dry cleaning. And you generally can’t iron it. On the upside, it sheds wrinkles easily (just hang the garment up overnight or, if you must, steam it).

Polyester

Nothing sounds worse than polyester clothing. Just the mere mention of it brings to mind all those sweaty and uncomfortable polyester suits during the 1970s (the ones in Saturday Night Fever? Yea, those were polyester).

But polyester was not always viewed with such disdain. In the period following WWII, polyester suits were considered techwear, like Nike’s ACG today. This was the era of the wash-and-wear suit, which blended man-made and natural fibers. As the story goes, one summer morning in 1946, while attending a conference in Florida, Joseph Haspel put on his suit and waded out into the Atlantic Ocean, all the way up to his neck. As stunned beachgoers looked on, Haspel returned to shore, went to his hotel room, and hung his suit up to dry. Hours later, he resurfaced as a dinner banquet wearing the same outfit, looking perfectly presentable and convincing attendees that such suits were the wave of the future.

A few years later, Dupont debuted a suit that was made of a fiber they called Dacron (which, for all intents and purposes, is a fancy name for polyester). The suit had been worn for 67 days without a pressing. It had been dunked twice into a swimming pool and then machine washed. And to everyone’s surprise, it was still perfectly wearable. Hart Schaffner & Marx picked up the fiber in 1953 for a new line of Dacron-wool blend suits; Brooks Brothers began using the man-made fiber for shirts, soon following with suits.

All this was made possible because of polyester, which is hydrophobic (which means it repels water). It’s strong and flexible, resists wrinkling, and is machine washable. This is why you’ll often see polyester used for outerwear (Gore-Tex is an evolution of polyester). It’s also sometimes mixed with cotton to produce wrinkle-resistant shirts. And if a spinner is using a weak or fragile fiber, they’ll sometimes mix in a bit of polyester to strengthen a yarn.

At its worst, polyester clothes can look cheap and unnatural. When worn next to the skin, sometimes it’s not very breathable and can feel clammy. But technology has come a long way since polyester was first introduced, and much like fused suits — which are often said to bubble, even if modern ones rarely do — today’s version isn’t always deserving of its bad reputation. Microfibers, for example, are made from polyester and are often used in garments with great success. A lot depends on the specific yarn and how it’s used.

When You Want Polyester: Since the fiber is hydrophobic, it works great for outerwear and gym clothes. It’s water repellant and, depending the weave structure, can also be breathable. Nike’s Dri Fit fabric, for example, is made from a stretchy form of polyester. It keeps your skin dry when you’re working out, so you don’t get that clammy sensation of sweaty cotton sticking to your skin. Fleece outerwear, such as Patagonia’s Retro-X, is also made from polyester.

When You Want to Avoid Polyester: Polyester doesn’t always age that well, and depending on the fabric, it can make a garment look cheap. It’s also subject to static and mildew. Generally speaking, for men’s clothing, you should be fine with polyester if it’s in outerwear or gym clothes. If you see polyester blended with a natural fiber for something else, maybe be a bit more suspicious. It may be that they’re using the material to strength a less-than-great, short staple yarn.

Elastane

The Atlantic has a great article this month by Amanda Mull, which talks about how jean manufacturers have been smuggling spandex into their clothes and marketing them as masculine to gender-sensitive men. “For something as innocuous as slightly less restrictive pants, stretch jeans have caused a lot of hand-wringing among men’s-fashion types over the past couple of years,” she wrote. “Much of it is bound up in what constitutes an appropriate performance of manhood, and whether suffering for fashion, something long considered a feminine burden, is something masculinity requires.” An excerpt:

There are two main ways that clothing companies have chosen to rebrand sitting comfortably as an activity for men. The first is recoding stretch denim as an aid in athletic performance, even though modern fashion jeans aren’t intended to be worn for anything resembling exercise. It’s difficult to parse what kind of rapid motion Banana Republic expects its customers to undertake in Rapid Movement denim, for example, but evoking ideas of athleticism is a common tactic for brands trying to make a case to men for a historically feminine product, according to Ben Barry, the chair of the Ryerson School of Fashion. Invoking athleticism also helps conjure the comfort and ease of athleisure, which is used in other parts of men’s fashion—dress shoes with flexible, cushioned soles, for example—to promise buyers a more casual experience in disguise. […] The other idea that marketers have invoked to bring men over to the dark side of stretch pants is comfort, which appeals to a slightly less active, slightly less aesthetically concerned conception of modern masculinity. For men who wish they could wear their sweatpants to the office, both traditional brands and upstarts like the Kickstarter darling Alday are here to give them the opportunity. In doing that, they indulge the masculine belief that men should think about how they look as little as possible. There’s clearly a market for such a product: Alday’s Kickstarter sought to raise $15,000, but it ended up with more than $67,000 in support from backers who want to try a denim product that’s knitted like pajamas.

In reality, elastane (the generic name for Lycra or spandex) has been in men’s clothing for years. Without spandex in your socks, they’d bag and fall down. Without it in your boxers or briefs, you wouldn’t be able to keep your underwear up. Elastane is strong, machine washable, wrinkle resistant, and (obviously) very stretchy, with a spring back quality that helps yarns keep their shape. On the other hand, they don’t breathe very well and, eventually, they break down. If you’ve ever heard the “click click click” sound on an old spandex waistband, that’s basically the rubber snapping. And it can’t be repaired.

When You Want Elastane: When you want a bit of stretch to a garment.

When You Want to Avoid Elastane: Elastane is only ever added to a garment when it needs to be stretchy. So the only time you’d want to avoid it is if you dislike stretchy garments.