Short answers, pulled from the story.
Isaiah was an 8th-century BC Israelite prophet after whom the Book of Isaiah is named. His name means "Yahweh is salvation," and he is also known as Isaias or Esaias. He prophesied during the reigns of the kings of Judah Uzziah, Jotham, Ahaz, and Hezekiah.
Isaiah began his ministry probably in the 740s BC, a few years before the death of King Uzziah, whose reign lasted 52 years in the middle of the 8th century BC. He may have prophesied for as long as 64 years, possibly into the reign of Manasseh.
The Bible and other primary sources do not specify the time or manner of Isaiah's death. The Talmud says he suffered martyrdom by being sawn in two under the orders of King Manasseh, in a tradition where he hid inside a cedar tree that was then sawn asunder.
Isaiah encouraged King Hezekiah to resist the Assyrians when Sennacherib's army threatened Jerusalem. According to the account in 2 Kings 19, an angel of God fell on the Assyrian army and slew 185,000 of its men in one night, after which Sennacherib made no more expeditions against Judea or Egypt.
In Christianity, figures such as Jerome called Isaiah "more of an Evangelist than a Prophet," and the songs of the Suffering Servant are read as prophecy of the death of Jesus Christ. In Islam, Isaiah is not named in the Quran or Hadith but appears as an accepted prophet in sources such as the qiṣaṣ al-anbiyāʾ and tafsirs.
In February 2018, archaeologist Eilat Mazar announced the discovery of a small seal impression reading "belonging to Isaiah nvy" during the Ophel excavations south of the Temple Mount in Jerusalem. It was found only 10 feet from a bulla bearing the inscription of King Hezekiah of Judah, though damage to the seal casts doubt on whether it confirms the word "prophet".