In physical stores, the process is straightforward: you show your ID, the cashier checks the date, and you're good. Some stores might use a scanner that reads the barcode on your license.

Online is where it gets more interesting. Most reputable sellers use a third-party service that cross-checks your name, birth date, and address against public records. Sometimes you'll need to upload a photo of your ID or take a quick video selfie. It might feel intrusive, but it's actually protecting you—and the seller.

Some stores will also require an adult signature upon delivery. That's another layer of verification, and it's a sign they're following the rules.