Ask any derm: Of all the beauty products in your arsenal, sunscreen is by-and-large the most important, but it also happens to be the most confusing. As words like “mineral blockers,” “broad spectrum UV,” and “reef safe” become more common in the conversation surrounding sun protection, it’s critical to understand what the heck all of those ingredients on the label actually mean.

“In the United States, sunscreen manufacturers are required to list the ingredients active and inactive ingredients on the label. The active ingredients in sunscreens are the UV filters that protect our skin from UV rays. The inactive ingredients are the carrier lotion that holds the UV filters,” says Terry Zickerman, founder of Love Sun Body. “The active ingredients can be chemical, mineral, or a combination of both. Similarly, the inactive ingredients can be chemical, natural or a combination of both.

First up: Understanding the different types of sun protection products out there on the shelves. There are two different types of sunscreen ingredients on the market—”physical” and “chemical”—both of which protect your skin from the sun’s rays, but in different ways. Physical sunscreens create a literal physical barrier between your sun and the skin to form a protective barrier, while chemical sunscreens sink into your skin to absorb the UV rays.

Chances are you’ve heard some rumblings about this, as the FDA recently called into question the efficacy and safety of certain SPF ingredients. Don’t rush to check your SPF stash just yet, though: This announcement is basically just saying that we need more research when it comes to the ingredients used in our chemical filter SPFs. “The chemical sunscreen ingredients we have available in the United States are effective in blocking ultraviolet light,” says New York-based dermatologist Joshua Zeichner, MD. “There is no definitive data that they are harmful to our health, and the benefit of using them outweighs any potential risk.” As cosmetic chemist Ginger King adds, while “chemical sunscreens are okay to use for humans, they’re not always friendly to coral reefs and fish” so make sure to look for options that are reef safe if you’re taking a dip in the ocean. However, she notes that they’re a good alternative for anyone  who finds mineral sunscreen to be too thick, or for those who simply prefer the feeling of a chemical lotion.

When it comes to UV rays, there are two primary types that you need to worry about: UVA, which penetrate the deep layers of your skin to cause aging and wrinkles; UVB rays hit the top layer of the skin and lead to sunburns and, over time exposure to both could lead to skin cancer. So in order to ensure you’re completely protected, you want to use a product that will work against both.

While mineral filters are able to work double duty to keep you safe from both types of rays (lookin’ at you, zinc oxide and titanium dioxide!), when it comes to chemical ‘screens you’ll need to opt for something that has a thoughtful combination of UVA and UVB protectants, which is why you’ll frequently see a few active ingredients in chemical sunscreens. Since not all ingredients (and thus, sunscreens!) are created equally, we broke down the most important ones—and what you should know before slathering them all over yourself this season.

UVB Protection

Octocrylene: Octocrylene is the most highly stable of the UVB blockers, and is a great option if you want to go the chemical route. Some sensitive-skinned peeps have found that it can cause irritation, so it’s best to do a patch test before rubbing it all over your face and body at the beach.

Octisalate: Consider octisalate your “middle of the road” UVB ingredient. It degrades slightly when exposed to sunlight, so it’s not quite as potent as octocrylene. In addition, it needs to be combined with another UVB-blocking element in order to actually provide enough protection to your skin.

Octinoxate: When it comes to blocking out UVB, octinoxate has got you covered—it’s one of the most popular UVB blockers in the industry. But, it’s worth noting that it, too, can degrade when exposed to sun. “When octinoxate is exposed to sunlight, it is changed to a less UV-absorbent form, which would seem to compromise its effectiveness,” says Zickerman, pointing to a few pieces of evidence to back this claim. It’s also not classified as a “reef-safe” sunscreen, so it’s worth skipping if you’re planning on hitting the beach.

UVA Protection

Avobenzone: Of the two chemical UVA blockers, avobenzone isn’t a highly stable ingredient on its own, and needs to be paired with one that offers UVB protection. “Chemical sunscreens are absorbed into the skin and absorb UV radiation—upon being exposed to UV rays, they break down and release heat into skin,” explains Zickerman.

Broad Spectrum

Oxybenzone: Oxybenzone, a chemical compound, is technically a broad-spectrum ingredient, but it only protects against short UVA rays—not long ones, so you’ll usually see it paired with other ingredients on a label. Aside from that, though, oxybenzone has an entirely different set of things to think about when using it: It was one of the other major offenders to the reefs cited in Hawaii’s legislation, and the EWG has rated it as a level 8 out of 10, because some preliminary research has shown that it could have effects on health. More studies need to be done on oxybenzone (and every other ingredient out there, TBH), but even still, it’s a widely used ingredient.

Titanium dioxide: There are two mineral ingredients that the FDA has approved as broad spectrum blockers. Titanium dioxide protects against UVB and short UVA rays, making it a staple in most mineral ‘screens. “For anyone with sensitive skin in particular, they can have a hard time finding sunscreens, as most are made with chemical UV blockers,” says dermatologist Shari Marchbein, MD, who works with CeraVe sunscreens. “Instead, they should look for physical blockers like zinc oxide and titanium dioxide which provide excellent broad spectrum sun protection.”

Zinc oxide: This brings us to dermatologists’ (and lifeguards’) favorite sunscreen ingredient: zinc oxide. It’s highly stable, and protects against UVB rays and both short and long wavelengths of UVA. Zickerman suggests looking for formulations that are at least 20 percent zinc oxide, because at low concentrations, the UVA protection becomes insufficient. While there’s some debate over the nano versus non-nano particles in mineral sunscreens (according to King, nanoparticles aren’t great for coral reefs), Dr. Zeichner notes that he prefers nano formulations because they blend more seamlessly into skin. ‘There’s no definitive data showing that nano particle mineral blockers are harmful to our health,” he says. Just consider opting for the non-nano stuff if you’re hopping in the ocean on a day at the beach.

This post has been updated from its original version

Here’s why you should be wearing sunscreen 365 days a year, plus our favorite mineral sunscreens to help you do it.