Rabi Al Thani, which is formally known as Rabi al Aakhir, is the fourth month of the Islamic calendar and it is the month which comes after Rabi ul Awwal. Rabi ul Thani 2023 starts from 17 October to 18 August 2023. The word "Rabi" means "spring" and Al-thani means "the second" in Arabic language, so "Rabi' al-thani" means "The second month of spring" in Arabic language. The name seems to have to do with the celebration events in the month as "spring" is the end to winter (symbol of sadness) and consequently the start of happiness.
The Islamic calendar is a lunar calendar, and months begin when the first crescent of a new moon is sighted. Since the Islamic lunar calendar year is 11 to 12 days shorter than the tropical year