Diwali, or the festival of light, is celebrated to honor the return of Lord Ramachandra, Sita Devi and Lord Lakshmana to the city called Ayodhya.
King Dasaratha had a kingdom in a beautiful place called Ayodhya. He had three wives, one of whom was Kaikeyi. Kaikeyi had once saved King Dasaratha’s life during a war, thus getting two boons from the king.
Dasaratha had four sons, the eldest of whom was Lord Ramachandra, who was a popular person among all. Lord Ramachandra was married to Sita Devi. Just before Ramacandra’s coronation, Kaikeyi requested these two boons from Dasaratha, which she had received from him. She requested that his son Bharata be crowned king and Lord Ramachandra be exiled for 14 years. All wishes were fulfilled.
Later, Dasaratha passed away heartbroken. When the last year of exile was going on Sita devi was kidnapped by the demon king Ravana. Lord Ramachandra later killed the demon and freed Sita Devi.
When the 14 years of exile were over and it was time to return to Ayodhya, the entire kingdom was decorated with ghee lamps. This ending of 14 years of exile and subsequent return to Ayodhya is celebrated as Diwali.