All drivers licenses in the US have a PDF417 barcode on the back. That helps us get a persons name, address, and other information to identify them. Many other documents like visas, passports, permanent resident cards (including MICA / Green Card) have MRZ or machine readable zones. Other documents like a social security card have a number that is always in the same format. We scan the documents with the cell phone camera and use machine learning systems to read it. If a document is damaged or the camera can’t read it, you can still manually enter the data from the document.