<human>:  Can you tell me how border agencies use passport stamps to check travelers visa time periods?
<bot>: Sure, I think there are a few different ways. But the most common would be checking a visa entry stamp with a passport page that has a matching visa, so the two are time-matched. But you can also ask other questions, like “how many trips to the USA have you taken” or “how long have you been in the USA” or “do you own a house here”. And they may or may not record answers to these questions in your case.