The correct answer is Personal Identification NumberShort for a personal identification number, the PIN is a set of personal numbers used to prove positive identification. It is often used with automated bank teller machines, telephone calling cards, and accessing Wireless networks. Because PINs protect much of your information and resources, its wise to use a PIN that is difficult to guess.Avoid including the following items in your PIN-Simple number sequences like 1234 or 0000Sequences of repeated numbers like 1122 or 2233Significant dates, such as your birth year or spouses birthdayAny part of your Social Security numberAny part of your address or phone numberLonger PINs are safer than shorter PINs. If you use a four-digit PIN, there are 10,000 possible variations (starting with 0000, 0001, 0002, and so on). With a six-digit PIN, there are 1 million possible codes.Longer PINs work well because it takes more attempts to guess them. Most security systems lock your account after a set number of attempts. This ensures it is harder for thieves and computer programs to successfully guess your PIN.