PAN card is a ten-digit alphanumeric number, issued in the form of a laminated card.
It is now mandatory for all Financial and real estate transaction, Bank Account Opening etc.
Holding PAN card will not automatically open up your tax file with Income tax Department.
PAN Card is one time process and need not to be applied again and again.
If we define PAN, it is Permanent Account Number. A 10 digit alphanumeric code, first 5 alphabets, 4 numbers and one alphabet at last (like AAAPC9999P).