What are highlights and how do they work?

Highlights are one of the most popular salon services in the world, and also one of the most misunderstood. The basic idea is simple: rather than changing the color of every single strand, highlights selectively lighten certain sections to create a multi-tonal, sun-kissed look. But the process behind that effortless finish is actually quite complex.

Here's what's actually happening when you're sitting in that salon chair.

Foil highlights vs. freehand painting

There are two main ways to apply highlights, and they give you different results.

Foil highlights are the classic approach. Your colorist takes fine sections of hair, applies lightener (bleach), and wraps each piece in a foil. The foil traps heat, which speeds up processing and keeps each section separate. Because everything is controlled and enclosed, foils give the colorist a lot of precision over where the color goes, how light it gets, and how consistent it is throughout. The result tends to be more defined and higher-contrast. One trade-off is that as your hair grows, the regrowth line becomes visible fairly quickly, usually around six to eight weeks.

Freehand painted highlights (balayage) work differently. Instead of foils, the colorist paints lightener onto the surface of the hair with a brush. This creates a softer, more blended finish that grows out much more gracefully.

Where highlights are placed

Placement has a huge effect on the final look. Your colorist will usually talk you through a few options.

Face-framing highlights focus on the sections closest to your face, including the front layers, temples, and hairline. They brighten your complexion and give a softening effect without changing the overall look of your hair too dramatically. These are a great low-commitment starting point if you've never colored your hair before.

Money-piece highlights are a bolder version of face-framing, with a concentrated, often striking panel of lightened hair right at the front, usually starting from the root. Think high-contrast statement piece.

All-over highlights are exactly what they sound like: lightened sections distributed throughout the entire head. This takes the longest and creates the most comprehensive tonal change.

Do highlights always need bleach?

Overwhelmingly, yes. Hair gets its color from melanin, a pigment that sits inside the cortex (the core) of each strand. To lighten hair, you have to break that melanin down. The only way to do that is with an oxidative lightener, which is what's found in bleach formulas.

Regular hair dye and semi-permanent color cannot do this. They work by adding pigment, not removing it. So for any highlighting service, whether it's foils or balayage, a lightener will always be part of the process on the sections you want lifted.

What about dyeing over highlights?

This is one of the most common questions colorists hear. The short answer: it's totally possible, but you need to understand that highlighted sections behave very differently from your unlightened hair.

Bleached strands are porous. The lightening process has compromised the outer layer of the hair, which means those sections absorb new pigment faster and lose it faster than intact hair. When you apply color over highlighted hair, the bleached parts will grab it more aggressively, often pulling darker or ashier than you wanted. This is especially common with box dye applied over blonde highlights.

If you're trying to go darker over highlights or blend them back toward your natural color, a professional toning or color service is really the way to go, at least the first time around.

Balayage vs highlights: what's the real difference?

Balayage has been the most requested salon color technique for well over a decade now. The word comes from the French balayer, meaning to sweep, and that's essentially what the colorist does: sweep lightener across the surface of the hair in a freehand motion, concentrating it toward the mid-lengths and ends while leaving the roots relatively dark.

The result is a gradient that goes from darker at the root to lighter at the ends, with transitions that look naturally grown-in. It works beautifully on brunettes and blondes alike, and it's the technique most associated with that effortless, lived-in look.

Why balayage looks more natural than foil highlights

It all comes down to how the lightener is applied and what that means for your grow-out.

With foils, lightener goes on from root to tip in neat, uniform sections. As your hair grows, there's a clear line where the natural color ends and the lightened section begins. It looks deliberately colored in a way that requires regular maintenance.

With balayage, the root is intentionally left darker and the lightener is feathered in gradually as it moves down the strand. When new hair grows in, it blends into the existing color rather than creating a sharp contrast line. That's why balayage clients can often go four to six months between appointments without their hair looking noticeably grown out.

The bleaching process in balayage

Balayage still involves bleach. There's no getting around that. The main difference from traditional highlights is that because the lightener is painted onto the surface of the hair rather than sealed in a foil, there's less processing heat involved. This generally means a gentler lift, though it can sometimes be slower, and the results have a naturally variable quality that contributes to that organic, imperfect look.

One thing experienced colorists always account for is that the degree of lift varies along the strand. Ends that have been through previous balayage sessions are usually more porous than the mid-lengths, so the same lightener formula will behave differently in different zones of the hair. That's part of what makes balayage a skilled service.

Why balayage-treated hair has unique care needs

Because the bleached sections run from mid-shaft to ends, balayage creates a specific challenge: your roots are essentially virgin hair, while your ends may be significantly more fragile. This difference in porosity means different sections of the same strand have different moisture needs, different elasticity, and different responses to heat and products.

Porous ends absorb water quickly but struggle to hold onto it. That's why balayage hair often feels dry or prone to breakage at the ends even when the roots feel perfectly fine. A routine that only addresses one zone will underserve the other.

The most effective approach is to give extra moisture and protein support through the mid-lengths and ends, handle the hair gently throughout, and be realistic about what will happen if you try to color over it at home.

Lowlights: adding depth and dimension

Lowlights don't get talked about nearly as much as highlights, which is a shame because they can be genuinely transformative. While highlights selectively lighten sections of hair, lowlights deposit darker color into selected sections to add depth, contrast, and dimension to hair that might otherwise look a bit flat or one-dimensional.

The application method is the same as foil highlights: sections are isolated, color is applied, and the hair is wrapped in foil while it processes. The difference is what's inside the foil. Instead of lightener, it's a darker shade, usually one or two tones deeper than the base color.

Who lowlights are for

Over-highlighted hair that has lost its depth over time. Regular highlight services can gradually take hair lighter and lighter until everything looks uniform and a little flat. Weaving in some lowlights restores the contrast that made the highlights look interesting in the first place.

Very light hair that looks one-dimensional. Platinum or pale blonde hair can appear almost shadowless in certain lights. A few well-placed lowlights add the movement and depth that make color feel alive and intentional.

Anyone gradually transitioning away from highlights. Going from heavily highlighted hair to a more natural look in a single session is tricky and often results in uneven or brassy color. Lowlights offer a more gradual, natural-looking transition over a couple of appointments.

They're also used for grey blending, where a colorist weaves lowlights around silver or grey sections to soften the contrast for people who aren't quite ready to fully embrace or fully cover their grey.

Do lowlights damage hair?

Significantly less than highlights, because lowlights don't require bleach on the sections being treated. Depositing color is a much gentler process than lightening. That said, if surrounding sections have already been highlighted and are in a compromised state, the overall care approach for that head of hair still needs to address porosity and moisture balance.

What bleaching actually does to your hair

Bleach gets used as a catch-all word, but here we're talking specifically about the oxidative bleaching process: a chemical reaction that uses hydrogen peroxide and persulfate salts to break down melanin inside the hair cortex and lift hair toward blonde, platinum, or white.

Understanding this isn't just trivia. The changes bleaching creates are permanent, and they determine everything about how bleached hair behaves, what it needs, and why it's so prone to damage when not cared for properly.

How oxidative bleaching works

Hair gets its color from two types of melanin: eumelanin, which creates brown and black tones, and pheomelanin, which creates red and yellow tones. Both are large molecules embedded inside the hair's cortex, which sits beneath the protective outer layer called the cuticle.

To reach the cortex, the bleach formula first has to get through the cuticle. It does this by swelling the hair shaft and lifting those scale-like outer layers apart. Once it's inside, the oxidative reaction kicks off: hydrogen peroxide generates oxygen radicals that break the melanin molecules into smaller and smaller fragments until the pigment is effectively gone.

As this happens, hair moves through a predictable sequence of tones: black, then brown, then red and orange, then gold, then pale yellow, and finally white. The further along that spectrum you want to go, the longer the bleaching process has to run.

The three types of bonds and why they matter

While the melanin is being broken down, bleaching also affects the protein bonds that hold your hair's structural scaffold together. This is where the real, lasting damage happens.

Porosity: why bleached hair is a different material

Once bleached, the cuticle never quite closes back to its original state. The scales stay slightly raised and damaged, which is what colorists mean when they talk about bleached hair being porous.

Water absorption. Porous hair soaks up water almost instantly. But it releases that water just as quickly, which is why bleached hair tends to feel dry and struggles to stay moisturized.

Color absorption. Porous hair grabs pigment fast. This can be useful for toning, but it also means applying new color over bleached hair requires care and sometimes dilution to avoid over-depositing.

Heat sensitivity. The compromised cuticle gives far less protection against heat damage. Styling on already-porous hair accelerates breakage. If you bleach your hair, reducing your heat tool temperatures and always using heat protection is the single most impactful change you can make.

How to care for color-treated hair

Color-treated hair, whether it's been bleached, toned, dyed darker, or anything in between, has different needs than untreated hair. The more processing involved, the more intentional your care routine needs to be. Here's the essential framework.

Shampoo, conditioner, masks, and leave-ins: what to use and when

Once you understand what your hair actually needs, building a routine becomes much simpler. Here's a breakdown of each product category and how it fits into caring for color-treated hair.