What does go-to rate mean?

When at the starting period using a credit card, rates are usually set as being lower (the introductory period). After this period, which may vary depending on the issuer (some months, up to 1 year), the higher interest rate becomes active for the rest of the term. So, the go-to rate is actually what you have to check before opting for a credit, because this will indicate the ‘correct’ interest rate you will be paying 90% of the term.