Introduction and historical background, Babylon had conquered Judah and taken away a number of young nobles. Daniel's character is firmly established when he decides not to eat the unclean food prescribed by the king. His position in the government is established when he is able to tell Nebuchadnezzar his dream and its interpretation.
After the incident with the fiery furnace in Daniel 3, Nebuchadnezzar has a second dream. The interpretation by Daniel is a dire warning that the king is being watched and his behavior evaluated. Chapter 4, written in Aramaic, is Nebuchadnezzar's testimony about what happened to him and to the power of God.
Belshazzar's feast marked the end of the Babylonian Empire which was succeeded by the Medes and the Persians. Daniel rose to prominence in that empire as well. His success inspired jealousy and intrigue within the government. The other high officials conspired to frame Daniel. That did not go well for them. The king realized what was going on and God delivered Daniel from the lions. Thereupon, the conspirators and their families were fed to the lions.
Daniel has a vision of four beasts. These beasts correlate with the four metals on the statue in Nebuchadnezzar's dream. Where the king saw a magnificent statue representing the empires of the earth, God showed them to Daniel as dangerous animals. The vision correlates with John's vision in Revelation.
At the end of the Babylonian Empire, Daniel was given a vision of what was to follow. The vision was puzzling to him so the Archangel Gabriel was dispatched to help him understand. Competent Bible scholars differ on the scope of that vision.
Realizing that the 70 year exile to Babylon was nearing completion, Daniel humbly prayed for his people. His prayer was answered by Gabriel who gave him a prophecy of what was to happen to his people.
During this discussion there is a chart with a summary of the standard interpretation of the 70 weeks. https://www.addeigloriam.org/commentary/ot-prophets/seventy-weeks-of-daniel.htm
Daniel prayed and fasted for 21 days seeking to understand the oracle that had been revealed to him. The fact that it took Gabriel 21 days to burn through spiritual interference gives some insight into conflict in the unseen realm. The interpretation covered the period starting with the death of Alexander and extending to end times.
