Like a traditional conditioner, a leave-in conditioner is a hair care product that you apply to your hair after shampoo. However, you don’t rinse out a leave-in conditioner.

You can use a leave-in conditioner in conjunction with a rinse-out conditioner or on its own, but it should be applied to towel-dried hair and combed through to evenly coat your hair.

Once you’ve worked the conditioner into your hair, style your hair as you normally would.

Unlike traditional conditioner, which you rinse out of your hair, a leave-in conditioner stays in your hair even after it’s dry. This allows it to continue conditioning your hair throughout the day.

Like traditional conditioner, the main benefit of a leave-in conditioner is that it provides hydration for your hair. Applying leave-in conditioner to wet or damp hair locks in moisture, which smooths and softens hair.

If you use a blow dryer, curling iron, or flat iron on your hair, a leave-in conditioner guards against damage from heat styling.

For anyone who has trouble with tangles or knots after showering, a leave-in conditioner provides extra slip that makes it easier to work a comb through your locks.

Because it smooths hair and minimizes frizz, a leave-in conditioner leaves your hair in perfect condition for styling. It can boost the styling power of your favorite gel, mousse, or pomade, too.

Leave-in conditioners are usually scented. The fragrances vary from sweet fruity scents to more herbal, woodsy notes.

However, if you have sensitive skin or particularly dry, damaged hair, it’s a good idea to look for a fragrance-free formula. Chemical fragrances can irritate sensitive skin and strip moisture from damaged hair.

Leave-in conditioners usually come in either spray or cream formulas. Both provide the same benefits, but one may work better than the other depending on your hair type.

• Spray

A spray leave-in conditioner is a water-based formula with a lightweight consistency. Sprays are ideal for fine or thin hair that would be weighed down by heavy creams. With a spray formula, you simply mist the leave-in conditioner over your hair, and work it through with a comb.

• Cream

A cream leave-in conditioner has a heavier, thicker consistency for more moisture. Creams are ideal for dry, thick, coarse, or damaged hair that needs as much hydration as it can get. To use a cream leave-in conditioner, dispense a small amount of the product into your hands, and massage it through your hair with your fingers. Follow up with a comb to make sure the conditioner is evenly distributed.

Leave-in conditioners typically contain hydrating ingredients that not only moisturize but help draw moisture to your hair.

• Glycerin is a humectant that attracts and retains moisture.

• Fatty acids like alpha-linolenic acid and stearic acid boost your hair’s shine, promote hair growth, and soothe dry, irritated scalps.

• Cationic surfactants like citrate, lactate, and propionate lubricate hair to make it easier to detangle.

• Proteins like keratin strengthen hair and heal damage and breakage.

• Plant oils like jojoba oil and olive oil hydrate, smooth, repair damage, and boost shine.

• Silicones like dimethicone and amodimethicone are lubricants that reduce moisture loss and make hair less porous and prone to frizz. Some silicones build up in the hair, though, so look for a formula that lists them lower down in the ingredients.

Leave-in conditioners range in price depending on the formula and the size. In most cases, you’ll pay between $4 and $70.

• Budget-friendly

A spray leave-in conditioner in a standard eight-ounce bottle usually costs $4 to $15.

• Mid-range

A spray leave-in conditioner in a 15- to 16-ounce bottle usually costs $12 to $20.

• Expensive

A spray leave-in conditioner in a 20- to 28-ounce bottle usually costs $18 to $32.

• Budget-friendly

A cream leave in-conditioner in a four- to eight-ounce bottle usually costs $5 to $18.

• Mid-range

A cream leave-in conditioner in a 10- to 16-ounce bottle usually costs $15 to $42.

• Expensive

A cream leave-in conditioner in a 20- to 34-ounce bottle usually costs $35 to $70.

• For the best results, apply leave-in conditioner to wet hair, so it absorbs more easily.

• While your hair should be wet, it shouldn’t be dripping. Dry it with a towel after washing to remove excess water.

• Focus leave-in conditioner on the areas of your hair that are damaged. In most cases, the ends of your hair require the most conditioning.

• Whether you use a spray or cream leave-in conditioner, it’s a good idea to work it through your hair with a comb to make sure it’s evenly distributed.

• Once you’ve applied your leave-in conditioner, style your hair as you normally would. Leave-in conditioner works as a heat protectant, so you don’t need to use a second product if you plan to heat style your hair.

Q. Can I use a traditional rinse-out conditioner and leave-in conditioner?

A. Yes. Leave-in conditioner is meant to provide additional moisture and protection, so it’s designed to be used in conjunction with traditional conditioner. Wash your hair with your favorite shampoo, and follow up with your usual rinse-out conditioner. Apply leave-in conditioner while your hair is still wet to add extra hydration. Leave-in conditioner also coats your hair to protect it from heat and environmental factors.

Q. Can leave-in conditioner be used on dry hair?

A. While most leave-in conditioners should be used on damp hair for better absorption, some can also be used as daily moisturizers. With these leave-in conditioners, you can apply a small amount to the ends of dry hair to hydrate and smooth. Be careful not to use too much leave-in conditioner on dry hair, though; it may leave your hair looking greasy.

Q. Can leave-in conditioner help with hair growth?

A. Leave-in conditioner won’t give you longer locks overnight, but if used with other hair products, it can help with hair growth. Most leave-in conditioners contain ingredients that strengthen your hair. As a result, your tresses are less prone to breakage.