When a format specifier includes symbols that vary by culture, such as the currency symbol included by the "C" and "c" formats, a formatting object supplies the actual characters used in a string representation of a numeric value. For example, a formatting object might supply "$" for the currency symbol. The formatting object for system-supplied numeric types is a System.Globalization.NumberFormatInfo instance. For DateTime instances, a System.Globalization.DateTimeFormatInfo is used.

IFormatProvider contains the IFormatProvider.GetFormat(Type) method. The consumer of an object should call this method to obtain a formatting object.