When it comes to frizz, all curls know the struggle. Whether it's a halo of flyaways, fuzzy, undefined ends, or hair that doubles in size at the slightest hint of humidity, frizz in any form can be a frustrating fact of life for curly hair. But knowing why frizz happens can help you take control of your curls, once and for all.The Science of FrizzA curl's shape is what makes it beautiful, but also more prone to frizz. Each strand's coils and curves expose gaps in the hair's cuticle (AKA its protective outer layer of overlapping cells). Humidity from the air sneaks in through those gaps, where it expands the hair shaft and causes curls to lose definition. The result: frizzy, undefined curls."Imagine tiles on a roof. They're fine when they're laying down, but once a few of them are off, it leaves the roof susceptible to damage," explains Ouidad Curl Advisory Board member Helen Wagmeister, a certified trichologist and hair stylist at Cosmo &amp; Company in West Palm Beach, FL. "The cuticle is your hair's first line of defense."<br />Top 5 Causes of Frizz <br />1. Over-CleansingJust like skin, hair has a natural protective barrier that helps keep essential moisture inside and acts as a shields against the elements. Aggressive cleansers strip curly hair of this barrier, leading to dryness, breakage, and frizz. To keep your curls frizz-free, choose a sulfate-free shampoo, and avoid washing your hair every day. Instead, co-wash or simply rinse your hair with water between shampoos, and only cleanse when your scalp is actually dirty.<br />2. DrynessLike a sponge, hair that's thirsty will try to soak up moisture wherever it can find it. This means that the drier your hair, the more susceptible it is to absorbing frizz-causing humidity from the atmosphere. Keep your curls well-hydrated by using a conditioner made for your curl type.3. An Open CuticleCurly hair's curving shape means its cuticle layer is naturally raised, with gaps in between the overlapping cells. These gaps allow moisture and nutrients to escape, and humidity to enter. To ward off frizz and help curls look healthier and shinier, you need to seal your hair's cuticle. Keeping curly hair's cuticle healthy and sealed is key to beating the frizzies. Conditioners and moisturizing stylers can help with this, including those from our Advanced Climate Control collection. Some products do this by coating strands with heavy ingredients, but those can build up and leave hair looking lackluster. Our new Advanced Climate Control collection is different. The four-step regimen uses Anti-FrizzNano Technology with Sericin, a natural protein derived from silk. The ingredient's teeny-tiny molecular size means it can squeeze in between the gaps in the cuticle to form a protective seal against humidity. This seal also locks hair's internal moisture inside, and helps to fill in gaps in the cuticle to defend against frizz so your curls can stay healthy and hydrated.4. DamageYou know that cuticle layer we just talked about? Damage from environmental aggressors can compromise it, too. Heat, UV rays, and even friction from combing and brushing all make hair weaker and more prone to becoming frizzy. To prevent damage, use a priming spray to protect hair from sun, styling, and tangles.5. HumidityThis is the big one, but you already knew that. Nothing makes curly hair turn frizzy faster than rain-forest-like conditions. That's because humidity disrupts the hair's internal hydrogen bonds, causing curls to shrink, frizz, and lose their definition. Luckily, the right anti-frizz styler can help.<br />Denise's loose curls, before and after using our Advanced Climate Control regimen<br /><br />Christina's tight curls, before and after using our Advanced Climate Control regimen<br />Cuticle-Smoothing Tips to Fight Frizz<br />In addition to caring for your curls with the Advanced Climate Control regimen, here are a few ways to keep your hair's cuticle happy and your curls frizz-free: - When shampooing, be gentle. Never bunch up your hair or scrub roughly. - When towel drying your curls, blot-don't rub. This will help keep your cuticle smooth. - Tugging at curls with a comb can damage the cuticle. Use a detangling primer to help your tools glide through hair with ease. - When blow drying, angle your diffuser so the air flows down from your roots toward the ends to ensure the cuticle lays flat.