It is sometimes customary for individuals to have two additional credit cards used for emergency backups.  This is more important when traveling.  Users wanting to restrict their spending with debit cards or cash typically carry two credit cards for emergency situations as well. 

With new debit card regulations limiting purchases at fifty or one hundred dollars per transaction, there might be more reasons to sign up for credit cards as well.  These regulations will require consumers to use an ATM, write a check, or use a credit card for any purchases over a designated limit.  Credit cards are no longer just for travel or unexpected frozen debit cards flagged for possible fraudulent activities.   

Using credit cards can also have their benefits as well.   A good hotel credit card can earn free stays at your favorite hotel brand along with being a back-up card.  Airline credit cards allow you to earn free flights and bonus miles by simply applying for one.  Cash back cards are ideal for those who prefer a more direct cash back rewards.  Cash back cards can earn you one percent or more off every purchase.