Define or not?

Hello,

I am trying to understand a line code ( RTC_DS3231 rtc; ) from the RTClib example but I have no idea what it’s meaning.

I thought it might be a #Define statement but the Arduino Reference Guide says that #Define IS necessary.

The line of code is…

// Date and time functions using a DS3231 RTC connected via I2C and Wire lib
#include <Wire.h>
#include "RTClib.h"

RTC_DS3231 rtc;

Is this some sort of declaration or shorthand variable?
Can you point me to correct reference guide so I casm learn more

Thank you

It is a declaration of an object/variable. The RTC_DS3231 is class defined in the header.
It is similar like int i; but variable type is a class.