Iyengar or Ayyangar is a caste

Caste

Caste is an elaborate and complex social system that combines elements of endogamy, occupation, culture, social class, tribal affiliation and political power. It should not be confused with race or social class, e.g. members of different castes in one society may belong to the same race, as in India...

 given to Hindu

Hindu

Hindu refers to an identity associated with the philosophical, religious and cultural systems that are indigenous to the Indian subcontinent. As used in the Constitution of India, the word "Hindu" is also attributed to all persons professing any Indian religion...

 Brahmins of Tamil

Tamil people

Tamil people , also called Tamils or Tamilians, are an ethnic group native to Tamil Nadu, India and the north-eastern region of Sri Lanka. Historic and post 15th century emigrant communities are also found across the world, notably Malaysia, Singapore, Mauritius, South Africa, Australia, Canada,...

 origin who follow the Visishtadvaita philosophy propounded by Sri Ramanujacharya. They are found mostly in Tamil Nadu as they are generally native to the Tamil Nadu state of the Republic of India. But they are also found in large numbers in Karnataka and Andhra Pradesh.

Iyengar are divided into two different sub-sects.