Yeah, the thick crema is basically a tiny foam cloud that’s the proof your grind and tamp are on point. Back in the 1600s people were still figuring out how to brew anything remotely espresso‑ish, but the real science kicked off in the 1900s with the first commercial machines. Those early pumps had to force water through finely ground beans fast enough to trap all those dissolved oils and carbon dioxide—exactly what makes that golden layer. The real trick is getting the pressure right—around 9 bars—plus the right grind size and a good tamp. If you mess any of that, the crema collapses faster than a bad latte art. So next time you hit that frothy top, know it’s a little espresso physics experiment you’re holding in your cup.