BIN=Bank Identification Number.
It will show you what bank is it and you can check what type of card is it. Forexample: classic, gold, plat, buiness, infinite etc etc..
The first 6 digits from the card number. The dump sellers give you binlist or you give them bins and after choose what bin works (in your location/area) and good for you.
If a bin starts with 4 ---> card is visa
If a bin starts with 5 ---> card is mastercard
If a bin starts with 3 ---> card is amex