Wikipedia
Iyer (also spelt as Ayyar, Aiyar, Ayer or Aiyer) is a caste of Hindu Brahmin communities of Tamil origin. Iyers are Srauta- Smartha Brahmana as they study Sruti and Smriti corpus of texts.
Iyers follow Uttara Mimamsa, also known as Vedanta by Veda Vyasa. Adi Shankaracharyas' commentaries and interpretations on Vedanta is known as Advaita Vedanta. Many Iyers are followers of Advaita Vedanta (philosophy propounded by Adi Shankara.), a subdivision of Vedanta: one of the 6 school of philosophies of Hinduism.
Recent historians of the 20th century have wrongly portrayed all Iyers as being Smarthas and being followers of Vedanta and Vedanga over the Vedas.
Iyers traditionally are Srauta- Smarthas Brahmana who study Sruti and Smriti corpus of texts. Vedanta is a school of thought of Hinduism and Vedanga means (Veda+Anga), meaning limbs of Vedas. They are pre requisite for any student of the Vedas They contain 6 parts which consists of Phonetics, grammar etc.
The majority reside in Tamil Nadu, India.
Iyers are sub-divided into various sub-sects based on cultural and regional differences. Like all Brahmins, they are also classified based on their gotra, or patrilineal descent, and the Veda they follow.
Iyers fall under the Pancha Dravida Brahmin sub-classification of India's Brahmin community and share many customs and traditions with other Brahmins. In recent times, they have felt affected by reservation policies and the Self-Respect Movement in the Indian state of Tamil Nadu. This has helped encourage a large migration to other parts of India and the English-speaking world.
Apart from the prevalent practice of using the title "Iyer" as surname, Iyers also use other surnames, such as Sāstri or Bhattar.