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Every source below was opened and read in full on the date shown before a sentence on this site was written against it. Sources read 11 August 2026.

National Coffee Association (About Coffee) · read 11 August 2026

Espresso uses high pressure to force nearly boiling water through finely ground coffee in about 20 to 30 seconds, and the guidance's quick numbers are a 1:2 ratio, one gram of dry coffee to two grams of brewed espresso, with 20 to 30 seconds of contact.
Espresso calls for a fine grind, like table salt, and a burr grinder is recommended over a blade grinder for a consistent grind that extracts flavour evenly.
The published brewing steps include distributing the grounds evenly in the portafilter basket, noting that special tools can help with this, then packing them into a compact puck with a tamper so the water saturates the grounds more evenly.
A digital scale is recommended for brewing more consistent espresso and keeping track of what worked.
Bitter or sour coffee may be ground too fine and over-extracted; flat or watery coffee may be ground too coarse and under-extracted.

National Coffee Association (About Coffee) · read 11 August 2026

Coffee's greatest enemies are named as air, moisture, heat and light, and the recommended storage is an airtight, opaque container in a dark, cool location.
The guidance recommends buying smaller batches of freshly roasted coffee, enough for one or two weeks, because coffee begins to lose freshness almost immediately after roasting.
Grinding is best delayed until immediately before brewing: with proper bean storage you grind the amount you need and keep the rest whole.
Roasted beans at room temperature are listed as retaining freshness for one to three weeks, and ground coffee for one to two weeks.
Coffee is hygroscopic: it absorbs and retains moisture, odours and tastes from the air around it, which is the argument for a truly airtight container.