The Puranas are ancient Hindu texts eulogizing various deities, primarily the divine Trimurti (Bramha, Vishnu and Shiva) in Hinduism through divine stories. Puranas may also be described as a genre of important Hindu religious texts, notably consisting of narratives of the history of the universe from creation to destruction, genealogies of kings, heroes, sages and demigods and descriptions of Hindu cosmology, philosophy, and geography. Puranas usually employ an abundance of religious and philosophical concepts. They are usually written in the form of stories. Sage Vyasa, is traditionally considered the compiler of the Puranas. Puranas existed in oral form before being written. Of the many texts designated 'Puranas' the most important are the Mahapuraṇas. These are said to be eighteen in number, divided into three groups of six.
The Puranas and their features are given below:
Sl No   Name of Purana   No of Verses   Main Contents
1   Brahma Purana   10,000 verses   Godavari and its tributaries.
2   Padma Purana   55,000 verses   Greatness of Bhagavad Gita.
3   Vishnu Purana   23,000 verses   Deeds of Vishnu and various ways to worship
4   Shiva Purana   24,000 verses   Greatness of Shiva, worshiping and other stories
5   Vamana Purana   10,000 verses   Areas around Kurukshetra in North India.
6   Markandeya Purana   9,000
verses   Devi Mahatmya, an important text for the Shaktas
7   Varaha Purana   24,000 verses   Describes various forms prayer and devotional observances to Vishnu. Also involve Shiva and Durga
8   Agni Purana   15,400 verses   Vastu Shastra and Gemology
9   Kurma Purana   17,000 verses   Second of ten major avatar of Lord Vishnu.
10   Bhagavad Maha Purana   18,000 verses   Most celebrated and popular of the Puranas telling of Vishnu's ten Avatars. Narrates the deeds of Krishna
11   Linga Purana   11,000 verses   Magnificence of Lingam, symbol of Shiva and origin of the universe
12   Narada Purana   25,000 verses   Greatness of Vedas and Vedangas.
13   Skanda Purana   81,100 verses   Birth of Skanda or Karthikeya, son of Shiva. The longest Purana, it is an extraordinarily meticulous pilgrimage guide, containing geographical locations of pilgrimage centers in India, with related legends, parables, hymns and stories
14   Garuda Purana   19,000 verses   Describes death and its aftermaths.
15   Matsya Purana   14,000 verses   Narrates the story of Matsya, the first of ten major Avatars of Vishnu. It also contains genealogical details of various dynasties.[
16   Vayu Purana   24,000 verses   Another name of Shiva Purana
17   Bhavishya Purana   17,000 verses   Ways to worship Devis, Krishna and Ganesha.
18   Brahmanda Purana   12,000 verses   Includes Lalita Sahasranamam.
The above 18 puranas are the foundation of Hinduism or Sanathana Dharma. These puranas give the full information of the universe, its existence, etc. These puranas came into existence through oral hymns. In these puranas one can find much information which is recently invented. The puranas which are into existence for thousands of years talks about the global form of earth, the movement of earth around the sun, height of Himalayas, number of continents, etc. From the information available in the puranas we can understand how much educated, knowledged and foresighted our ancestors were. In many puranas, it is noted what all may happen in the kaliyug and if we look at our surroundings we can find out what was mentioned in the puranas are what is happening now. As such puranas can be considered as the authoritative information about the universe.
By Premji