This 16-minute video will get you up to speed on espresso crema

Crema is the red-brown foam that sits on top of a freshly made shot of espresso. But what is crema, actually, and how is it formed? Coffee expert James Hoffmann made this video to explain.

He says that very early espresso machines did not produce crema. It wasn't until the mid-twentieth century, when high-pressure espresso machines were invented, that crema started appearing. At first, people weren't sure if crema was a good thing or a bad thing. In a savvy marketing move, the manufacturer decided to advertise its espresso as having "natural cream," turning a bug into a feature.