Iyers like all other Brahmins trace their paternal ancestors to one of eight rishis or sages. Accordingly they classify themselves into eight gotras, based upon the ancestor rishi. The term Iyer derives from the term Ayya used by the people of the Tamil regions to denote a respected person and are seen as representatives of Vedic Culture. The term is believed to have originated from the Sanskrit word 'Arya' which means a 'noble person'.
Iyers have many sub-sects among them, such as Vadama, Brihatcharanam, Vathima, Sholiyar or Chozhiar and Ashtasahasram. Each sub-sect is further subdivided according to the village or region of origin. Iyers do not have a single origin, as they have come to Tamil lands at different periods of time, for different reasons and from different parts of India, even though it has become common for them to intermarry in modern times. They also maintain a similar culture regardless of specific origin, due to cultural interaction for more than a millennium. It is possible that males of some sub-sects have intermarried with Dravidian castes, outside the Brahmin fold. The children of such marriages have generally acquired the caste of the mother.
Iyers follow one of the four Vedas - Rig Veda, Sama Veda, Yajur Veda and Atharva Veda. The Veda that an Iyer follows forms an important part of his identity, another being the gotra that he belongs to. The gotra is the name of the rishi who founded the clan one is born into. A woman belongs to gotra of her father until marriage, and then during kanyadaan changes to that of her husband.
There was formerly a lot of disunity among Iyer sub-sects over numerous issues. Such divisions and disagreements reduced with the adoption of Adi Shankaracharya as a teacher, by most Iyers. In later times, when many Vaishnava sects proclaimed themselves Iyengars, the word Iyer was used to usually refer to either Smarthas or to Saivaites. Contemporary Iyers are mostly smarthas and follow Adi