From Investopedia
No one wants to be bothered with another piece of mail or another email alert from their debt holders, but skipping over correspondence from your credit card company could cost you big. Credit card companies will occasionally send you a “change of terms notice,†which details the changes made to your credit card agreement. These changes go much further than updates in the privacy agreement, which typically just mentions that the issuer will not share your information with a third party.
These change of terms notices are also the ideal means of communication for credit card companies that want to let card holders know the financial amendments connected to their plastic. These changes vary from whether the interest rate has changed to if the cash advance fee has gone up (or down).