When it comes to fundamental physics, friction is great for things like stopping at red lights or avoiding slipping down the stairs, but not so great for your sex life. The good news is that you don't have to put up with friction during penetration with the help of your trusty sex side-kick: lube. If you've ever had questions about lube, though, you're not the only one that has been confused about how to use lube in bed, or what it even is. "Lube, or lubricant, is a liquid product that is used for sexual activity to make sex more comfortable by reducing friction," says Kelly J. Connell M.S. Ed., a sexuality expert.

"Using lube during sex reduces friction for numerous types of sexual activity including masturbation, anal sex, vaginal sex, oral sex, or sex with sex toys," adds Kim Airs, sexuality educator and director of the sexual health blog Grand Opening. Airs recommends using lube for any kind of sex, especially penetration, because it can prevent condom breakage and allow you and your partner to move easier and faster.

"When it comes to lube, the biggest misunderstanding is that there needs to be something wrong with you in order to need it," says Airs. Another common misconception, according to Airs, is that it's only for people with vaginas who aren't sufficiently aroused. That's not true — she says that lube can be used for a variety of reasons, including the simple fact that it can increase pleasure for everybody involved.

To use lube, dab a dime or quarter-sized amount to whatever area of the body you are about to be penetrating or stimulating and add more as needed. You will be able tell if you need more lube if you sense uncomfortable friction during penetration.

There are four kinds of lube: water-based, silicone-based, hybrids, and oil-based. Each has pros and cons, so it's important to figure out which kind is right for you.

Water-based lube usually has water and glycerin as the first and second ingredients, which washes off easily but tends to dry quickly. Water-based lube is frequently recommended because it's most compatible with bodies because they are also water-based, says Airs. Examples of water-based lubes include Sliquid ($20), which is glycerin free, and Astroglide's Ultra Gentle Gel ($6.59). "Water-based lubes are pretty much the more versatile of the lubes. They can be used with any type of sexual activity, including sex toy use, they're safe to use with condoms, and easy on the skin," says Connell.

Airs explains that silicone-based lube has a slippery, oil-like texture, is safe to use with condoms, and is more difficult to wash off than water-based lube, but doesn't dry out as fast. Most people like silicone for its smooth, slick texture and ability to last for a while. The big thing to remember about silicone-based lubes, according to Connell, is that you shouldn't use them on sex toys, because the silicone in the lube can break down and cause cracks in your silicone toys. These cracks could then potentially harbor bacteria and put you at risk for infections. Examples of popular silicone based lubes include Please Silicone Lubricant ($14).

There are also hybrid lubes with silicone and water that function similarly to silicone-based lubes with a slightly thinner texture.

For those who want a more natural product with only one or two ingredients, oil-based lubes like warmed up coconut oil or Cocolube ($29) are a great fit. However, oil-based lubes can be tricky, according to Connell. For those prone to bacterial infections, oil-based lubes are not recommended because they can linger in the body and cause a build-up of bacteria. "Oil-based lubricants are used for sexual activity however they can break down condoms, stain sheets, and be messy," says Connell. They can be a great choice for those who want a more natural lube during sex, but just remember that they aren't safe for condoms, she says.

‌Connell shares that things like Vaseline, anything with a petroleum base, Crisco, or anything that comes in a solid should not be used as lube. This is because, according to Connell, they can break down condoms and retain bacteria because the body doesn't flush them out on its own, which makes infection a risk. Spit isn't an ideal option, either; Connell explains it doesn't mimic lube's slippery effect and can potentially transmit infections.

"Lubricants are like perfume," says Airs, "the one that you like the most is the one that’s the best for you, and that is often different for everyone." She says that the best way to find a lube that works for you is to try a lot of small samples and see which one is most comfortable. To understand which lubes you'd like to try, consider the base and the sex you will be having with it. For instance, Airs explains that you always need lube for anal sex because the anus does not self-lubricate. Silicone-based lubes are therefore popularly used for anal sex because they don't dry out quickly. There are also numerous kinds of lube like Unbound's Clitoral Jolt Gel ($4) or Sliquid Organics Sensation ($15) that can add pleasurable tingling to your genitals with stimulating ingredients such as peppermint oil.

Overall, it helps to try out different samples of lubes to find the right one for you. To try out a few different kinds of lubes, slide on over to Babeland for its BabeLubette Sampler ($15) or to Unbound for its Oh! To Go Bag ($34). Here's to hoping you have zero friction in the bedroom after finding the right lube for you.