Ithihasas
Ithihas = Ithi + ha + sah = this + in this way + happened. So, ‘Ithihas’ represents something happened in the manner as mentioned. So they are not stories or myths. They are part of Indian history. 1. Ramayanam written by sage Valmiki and 2. Mahabharatam written by sage Vyasa come under this category. These are called history books.
Puranas
‘Puraapi navam ithi puraanam’ – It is modern even though it is old. It means even though Puranas appear to be old, they contain valuable knowledge that is equally applicable to the present modern society. Ithihasas and Puranas contain the same knowledge of Vedas but in a simplified story form. Even a layman can understand them and follow them easily.
There are 18 main Puranas along with another 18 sub Puranas. The following is the list of main Puranas: 1.Vishnu Purana, 2.Naradiya Purana, 3.Srimad Bhagavata Purana, 4.Garuda (Suparna) Purana, 5.Padma Purana, 6.Varah Purana, 7.Brahma Purana, 8.Brahmanda Purana, 9.Brahma Vaivarta Purana, 10.Markandeya Purana, 11.Bhavishya Purana, 12.Vamana Purana, 13.Matsya Purana, 14.Koorma Purana, 15.Linga Purana, 16.Siva Purana, 17.Skanda Purana and 18.Agni Purana.