"Shin Megami Tensei: Persona, known in Japan as PERSONA (ペルソナ, Perusona) is a series of role-playing games developed and published by Atlus. The series is a spin-off of the Megami Tensei series which focuses on demon summoners. However the Persona series centers around groups of teenagers who have the ability to summon facets of their psyche, known as Personas, into being. The first game in the series was called Megami Ibunroku (女神異聞録) in Japan which translates to "Record of the Goddess' Strange Tales," denoting a side story or alternate universe. The series underwent a drastic change in design during Shin Megami Tensei: Persona 3 which introduced elements of simulation games into the series which was continued in Shin Megami Tensei: Persona 4. Each title in the series utilizes a different method to summon Personas such as Evokers in Shin Megami Tensei: Persona 3 and Tarot cards in Shin Megami Tensei: Persona 4. While the North American localizations of the Persona series all carry the Shin Megami Tensei label, it is actually a completely separate series."
Source: Wikipedia, "Shin_Megami_Tensei:_Persona", available under the CC-BY-SA License.