To put it simply, conditioner is a conditioning or moisturizing agent generally made up of ingredients such as silicones, oils, and emollients, as well as cationic surfactants (the scientific term for soaps or detergents, which help to wash away the oily elements). When combined, these ingredients replenish hair’s moisture after some of it is stripped from shampooing.

There are various types of conditioner, too. Of the most common are — of course — your traditional post-shampoo hydrator; deep conditioner, which is almost like a hair mask in that it’s meant to be left on longer in order to penetrate the strands more deeply; cleansing conditioner (aka co-wash), which acts as a shampoo and conditioner hybrid that simultaneously cleanses and conditions the hair; and leave-in conditioner, a post-shower, no-rinse treatment that nourishes and protects the hair throughout the day.

There’s also dry conditioner now, which, according to cosmetic chemist Ron Robinson, is designed to spritz on just enough to make your hair shinier, smoother, and softer, without the risk of overapplying or making hair greasy.

Believe it or not, there is a right and wrong way to condition your hair. The right way, according to Los Angeles-based hairstylist Nathaniel Hawkins, is to apply the product in long, fluid motions, and to ensure you squeeze some of the water out of your strands after shampooing so that it doesn’t diminish the effects of the conditioner.

“Excess water dilutes your conditioner and prevents hair from soaking up moisturizing the ingredients,” he explains.

As far as how long you should leave it in for, Hawkins says two minutes should suffice, as this is approximately how much time it takes for the conditioner to adhere to the hair. If you’re using a deep conditioner, however, he says three to five minutes is ideal.

“Conditioner refortifies the cuticle with a protective coating, allowing the hair to keep growing and not break easily,” explains Washington, D.C.-based board-certified dermatologist Adam Friedman, who compares conditioner to cement filling a pothole. “When the hair is exposed to the outside world, the cuticle, or outer lining, gets damaged until it ultimately breaks; the conditioner fills in those injuries and coats the hair to assist the cuticle.”

Cosmetic chemist and author Perry Romanowski tells Allure the primary benefit of a conditioner is that it makes the hair much easier to comb through, though he says that there are several reasons one should use conditioner in their hair-care routine. “Conditioners also smooth the hair, detangle it, increase shine, reduce frizz, and make it feel nicer to touch,” he says.

“All you have to do is to wash your hair, only apply conditioner to one half of your head, then comb through the hair to notice the differences,” Romanowski suggests for any skeptics out there.

Conditioners smooth and detangle the hair, which, therefore, helps reduce breakage and split ends — and that’s precisely why New York City-based hairstylist Chuck Bass recommends conditioning every time you shampoo in order to add moisture back, as well as to soften and detangle. He’s not the only one who recommends this hair-care approach. “Any time you shampoo your hair you should condition it,” urges Romanowski. “It really makes the hair easier to comb and style.” There you have it.

This is almost a trick question: According to Romanowski, there actually isn’t a huge incentive to use conditioners based on your hair type. “In truth, there is not much measurable difference between products marketed for normal, damaged, color-treated, or curly hair,” he says. “Most modifications to the formula are done for theoretical reasons, but you probably wouldn’t be able to tell as a consumer that they are different.”

So, while the format of your conditioner may make a difference — for instance, a moisturizing conditioner might contain more oils and emollients to soften and smooth the hair — the composition of your typical post-shampooing conditioner doesn’t change a whole lot from formula to formula.

That being said, if you do have a particular conditioner that makes your strands feel exceptionally healthy and allows you to achieve your desired results, there’s nothing wrong with maintaining your diehard fan status for an old (or new) favorite.

All this to say: If you’re not conditioning your hair, you should probably start. But, don’t be fooled by the marketing terms and instead, try out a few different types or consult a hairstylist to find out what works best for you in terms of overall effect and personal preference.

Very few, though they do exist. Friedman points out that conditioners can be potential allergens for some people, which can cause allergic contact dermatitis. However, he notes that this would only be in a very low number of people. What’s more, if you’re acne-prone and fail to rinse out your conditioner thoroughly enough, it’s possible that you could break out on your face, neck, or body since conditioner can clog pores just like any product comprised of oils.

Another potential adverse effect of conditioners is that they can weigh the hair down. For instance, Romanowski says if you use more than a palm-sized dollop, or if you use a kind that contains a very high concentration of oils and emollients (read the label to find out) this can contribute to the hair looking greasy or flat. He notes that this is most common in people who have fine hair.

The simple answer: not-so-great things. According to cosmetic chemist Kelly Dobos, hair can become more brittle, susceptible to tangles, and prone to breakage with the absence of a conditioner.

“If you stop using conditioner, your hair will likely be more difficult to comb,” warns Romanowski. “It will also be more likely to have flyaways and frizz and be prone to splitting and breaking during your styling routine.”

Your hair may look duller and less shiny, he had, so there’s that. Do yourself a favor and just condition your hair, folks.