Fundamentals
What is coffee?
The cherry, the seed, the drink — how the plant becomes the cup, and why it matters when you're picking a bag.
Coffee, at the bar, is a brewed beverage. Coffee, at the shelf, is the roasted seed of the Coffea plant. The distance between those two definitions is where every real buying decision lives.
The plant
Coffea is a tropical evergreen. Two species produce nearly all commercial coffee: Coffea arabica and Coffea canephora (commonly called robusta). Both grow in a narrow band around the equator — roughly 25° N to 25° S — at altitudes and rainfall patterns that vary sharply by species.
The cherry and the seed
The fruit of the plant is a small red or yellow drupe called a coffee cherry. Inside each cherry are (usually) two seeds, flat-sided against each other. Those seeds are what get processed, dried, exported, roasted, and ground.
"Bean" is a convenient misnomer. It's a seed. The distinction matters when you read about processing: washed, natural, and honey all describe how the fruit is removed from that seed — and each shapes the cup differently. See processing methods.
Two species that matter
- Arabica — grown at higher altitudes, more delicate, higher acidity, more complex aromatics, roughly half the caffeine of robusta. Dominates the specialty market.
- Robusta — hardier, lower altitude, higher yielding, more bitter, heavier body, and significantly more caffeine. Historically undervalued in the specialty world; increasingly interesting as fine robusta programs mature.
The full contrast is covered in Arabica vs Robusta.
From roast to brew
Green (unroasted) coffee is grassy and unpalatable. Roasting drives the Maillard reaction and pyrolysis, developing sugars, acids, oils, and aromatics. Roast level — light through Italian — dictates a huge amount of what you taste; see roast levels.
Once roasted and ground, coffee becomes a beverage through extraction: water pulled through grounds under pressure (espresso) or by immersion/percolation (drip, French press, pour-over). The dominant lever is your coffee-to-water ratio.
Why it matters when you buy
Every honest label tells you three things that reflect the definition above: species (nearly always arabica unless stated), origin (where the plant grew, which shapes flavor more than any marketing copy), and roast (which shapes what's left in the cup). Anything else — "smooth," "rich," "premium" — is decoration.
That's the whole working definition. Everything on this site builds on it.