Brahma Purana is considered to be the first Purana out of 18 Puranas, which are also called Mahapuranas.
Brahma Purana is a text related to Lord Brahma who is equipped with Rajogun, therefore, this is also known as Rajas Purana.
Balambhatta has referred to it as Adi Purana (first Purana) in his commentary on the Mitakshara.
Also known as Saura Purana, because it includes many essential episodes related to Surya or the Sun God.
Brahma Purana covers Cosmology, Mythology, Genealogy, Geography, Manavantara (Cosmic Time Cycles), & other topics such as the human race, deity, animal, earth, hell, heaven, temple, pilgrimage, etc.