Short answers, pulled from the story.
Akhenaten was an ancient Egyptian pharaoh of the Eighteenth Dynasty who reigned approximately 1353-1336 BC or 1351-1334 BC. He was born Amenhotep IV, the younger son of Amenhotep III and Queen Tiye, and changed his name in the fifth year of his reign to reflect his devotion to the solar disc Aten.
Akhenaten introduced Atenism, a religion centered on worship of the Aten, the solar disc. By his ninth regnal year he had banned worship of all other Egyptian gods, defaced Amun's temples across Egypt, and declared himself the sole intermediary between the Aten and humanity. Egyptologists debate whether Atenism was strictly monotheistic, monolatristic, or henotheistic.
Akhenaten founded Akhetaten, known today as Amarna, around his fifth regnal year on a previously uninhabited site roughly halfway between Thebes and Memphis on the east bank of the Nile. A surviving boundary stela records that the site was chosen partly because it belonged to no god, goddess, ruler, or people who could claim it. Egyptologists believe the move may also have been aimed at breaking the influence of the powerful Amun priesthood based in Thebes.
The Amarna Letters are a cache of 382 diplomatic texts, mostly clay tablets, discovered between 1887 and 1979 near the site of Akhenaten's capital. They document correspondence between Egypt and rulers in Babylonia, Assyria, Syria, Canaan, Mitanni, and the Hittites. The letters show Akhenaten actively dispatching troops and monitoring vassal affairs, contradicting the older scholarly view that he neglected foreign policy.
After Akhenaten's death, his successors systematically dismantled his legacy. Tutankhamun returned the court to Thebes and restored traditional worship around 1332 BC. Horemheb ordered Aten temples demolished and their building blocks reused. Seti I then removed Akhenaten, Tutankhamun, and several others from official king lists to erase the Amarna period from the official record.
The identification remains contested. A mummy discovered in tomb KV55 in the Valley of the Kings in 1907 was studied by a team led by Zahi Hawass, with results published in 2010, identifying it as the father of Tutankhamun and "most probably" Akhenaten. Subsequent scholars have challenged the study, noting that the genetic markers could apply to a brother of Akhenaten such as Smenkhkare, and that the KV55 individual cannot be reconciled as the maternal grandfather of Tutankhamun's daughters under the proposed family tree.