Vyasa Dev- the most knowledgeable sage of all time was the son of Rishi Parashara and Satyavati.
Once Vyasa dev was in deep meditation. In his meditation, he composed a great epic in his mind. He was excited by the deep meaning of his work and wished to impart it to mankind. But he couldn't decide how to transform it into written form. Knowing his anxiety, the creator of the Universe Lord Brahma appeared before him and asked him his wish. Excitedly Vyas described to Him his conceived epic and asked for His help to suggest an expert who can help in putting the epic in written form. Brahma could find no one but Ganapati- the Lord of knowledge who could accomplish the job without any difficulty. He, therefore, advised the wise sage Vyasadev to render his heartfelt prayer to Shri Ganesh for His blessing.
Vyasadev then sat in meditation full of devotion to invoke Lord Ganesh. Eventually, Lord Ganesh was pleased and manifested himself before him with a smile. Without any delay, Vyasa urged Him to be kind enough to help him in writing his epic. Shri Ganesh happily agreed but put a condition. ‘I shall do that for you if you will never pause while dictating. Once my pen starts writing it will never stop till to the end.’
‘As you wish,' said Vyasa happily.
Thus, on an auspicious day, ‘The Mahakabya- Mahabharata’ was dictated by the great sage Vyasa and written by Lord Shri Ganesh. The whole epic was full of thousands of stories of different characters. It began with the glory of ‘Soma Vamshi’ and ended with the stories of Kauravas and Pandavas. Later Vyasa taught his epic to his son- Shuka who was well-versed in Veda and Vedanta. He also narrated the whole Mahabharata to his disciples among whom Vaishampayan was one.
While performing the great Sarpa Yagna, King Janamejaya humbly requested the noble Vaishampayana to narrate the whole episodes that his great-grandfather had composed. The kings, Rishis, and people present there wished for the same. Venerable Rishi Vaishampayan was excited to recite the Mahakabya he learned from his Gurudev- Vyasa. Among the Rishis Ugrashrava Sauti (Known as Sauta also)- son of Sage Lomoharsana was also there. He was a great rishi of his merit.
Once Sauta visited the Naimisharanya where he met the hard austerities ascetics. Beholding the wise sage Sauta, the ascetic Rishis requested him to accept their hospitality. And he agreed happily. During their conversation, the ascetics humbly asked him to recite the great epic of Vyasadev in front of them. Sauta was thrilled! Paying homage to the noble hearts, Sauta repeated the Mahabharata as told by Vaishampayana during Sarpa Yagna.
The whole epic was structured as a dialogue between Ugrasrava Sauti and the Rishi Saunaka with other ascetics in that forest- Naimisharanya.
The characteristic of Mahabharata is: It comprises- Historical, cultural, religious, literary, social, and geographical significance. like it's an encyclopedia of that era.