It’s peak cold and flu season, and mucus is making many of our lives miserable. But despite being a little icky, phlegm gets a bad rap. This germ-fighting goo contains cells and chemical compounds that help us power through a cold. You can also think of mucus as a traffic light for your health — what turns up in our used tissues can be a useful clue about the inner workings of our immune systems.

Reactions is joining PBS Digital Studios! Woohoo! To celebrate, we're doing a deep dive on the surprisingly complex and beautiful chemistry behind our favorite morning beverage: coffee. The chemistry of the universe is, in a way, in your morning cup of coffee — from the evolution of caffeine as a defensive chemical weapon in plants to the swirling eddies of milk and coffee fueled by diffusion, Brownian motion and other phenomena. After watching the video, you’ll never look at coffee the same way again.

As Donald Trump becomes president, huge questions remain about his policies affecting the central science. So we’ve started looking for answers. While presidents tweet, money talks. In this episode, we look how Trump’s economic stances could affect the dollars and cents of chemistry. Huge thanks to Kevin Trenberth and Cal Dooley for their help with this video.

CRISPR/Cas9 is making gene-editing cheaper and easier than ever before, but the creators are embroiled in a fierce dispute over who holds the patents to CRISPR technology. We went to the U.S. Patent and Trademark Office to get the lowdown on this dispute and in this episode, after hearing attorneys duke it out, Ryan Cross explains how the kerfuffle developed, and what the possible outcomes of the impending decision mean.

It’s almost time to ring in 2017. And since most New Year’s celebrations include alcohol, Reactions’ latest episode explains the chemistry behind its effects – drunkenness, frequent bathroom breaks and occasionally poor decision-making.

With the feasts and festivities of the holidays in full swing, we'll be kissing the passing year goodbye, but not without the addition of a couple extra pounds as a souvenir. Lucky for you, the winter also brings something that might actually help you lose that 2015 souvenir of yours: freezing cold weather. Today we're talking fat, and whether or not the shivering cold can help you shed a couple extra pounds.

Cast-Iron skillets are one of the kitchen's ultimate multitools with some big time advantages over your everyday, stock aluminum pan. Today we're taking a look at why these pans rule, and for you kitchen know-it-alls out there, pay close attention: we're using chemistry to prove the right way to season and treat a cast-iron skillet. Check out the Food Lab! - http://www.seriouseats.com/the-food-lab.

Vanilla is so common, some people use it as a dis. But watch out. This beloved bean may become a rarity.

So say you pour a beer but it’s all foam. Do you wait? Try to drink through it? Grab a straw. Just kidding. There is a better way. Find something oily like a french fry or a slice of pizza. Even your oily nose will work in a pinch. Get a dab of grease on your finger and swirl it through the foam and watch those bubbles disappear. Why? Well, you'll just have to watch the video, won't you!

Chemistry can do some wild tricks with food, letting you taste in a new way. Literally, in some cases. If you stick your foot in a bag filled with garlic cloves and rub them on the bottom of your foot, you will actually be able to taste garlic! It’s not because you have secret garlic taste buds on your feet. It’s because the molecules responsible for garlic’s smell (allicin) can penetrate your skin, get into your blood and travel to your mouth and nose, where you suddenly start to sense the taste of garlic.