What is a NOM number?

NOM stands for Norma Oficial Mexicana. Every certified tequila distillery gets a NOM number, and every bottle of real tequila has to print it — usually in small type on the back label. It tells you exactly where the tequila was made.

Here's why it matters: brands and distilleries aren't the same thing. A single distillery can produce dozens or even hundreds of brands under contract. NOM 1438 makes more than 300. So two bottles with completely different names, stories and price tags can come out of the same stills.

Some examples worth knowing:

• NOM 1139 is La Alteña, the Camarena family distillery behind both Tapatio and El Tesoro.
• NOM 1146 is La Fortaleza, run by Guillermo Erickson Sauza of the Sauza tequila family, which still makes tequila the slow, traditional way.
• NOM 1579 is El Pandillo, where Felipe J. Camarena makes G4 and Pasote.

Checking a NOM is the fastest way to separate marketing from production. If you love one bottle, look up its NOM — the other brands made there are a good place to look next. And if a "small-batch, family-owned" brand shares a NOM with 300 others, that's worth knowing too.