In addition to the deposits required at neighborhood location rentals, I was told at ATL airport, if the renter lives in Atlanta area, for example, the renter's credit card will be charged at least a $250 deposit hold upon rental pickup, to be released after the rental car return. Not sure exactly when it started, nor whether that's standard in other states.

For international rentals, a credit card deposit hold of some amount is usually required, depending on the respective location/country, along with the required insurance. Credit card insurance can generally be used, if proven for coverage (policy copy, or call to credit card issuer), but be prepared for the additional hassle with using that option and a higher deposit hold.