Aranayaka are texts that form the third constituent part of the
Vedas. Aitareya Aranayaka is the first Aranyaka in the Rig Veda.
Aitareya Aranyaka consists of 5 Aranyakas, which are
sub-divided into 18 chapters, and 75 Khandas.
The first Aranayaka consists of mantras, Nishkaivalya Shastra
and certain rights.
The second and the third Aranayakas are called the Upanishads.
The fourth and fifth chapter of the second Aranyaka constitutes
the Aitareya Upanishad.
The third Aranayaka constitute the Samhita Upanishad.