In contrast with all earthly kings, His days - that is, the Ancient of Days - are past reckoning. His days are infinite. He existed before time was established.
That is, millions and millions of beings standing or sitting here before the throne of God. According to the International Standard Bible Encyclopedia, Revised Edition, in Daniel 7:7-22, Ancient of Days refers to the venerable Judge who presided as the books were opened. He is of ancient tradition, the Father of years. The title Ancient of Days alternates with the title, Most High, found in Daniel 7:18-22.
In the original Aramaic, the term from which we get ancient also means venerable, as the International Standard Bible Encyclopedia stated, and by extension, respected, majestic, dignified, esteemed, honored, and revered. It is because He is with no beginning and no end, and is the Author of creation, that He is not only the Most High Sovereign, but He is supremely wise and just.
The prophet Daniel gives us an insightful look into the heavenly realm. Although God is spirit, which is normally invisible to the human eye, Daniel was permitted to see these two Beings in his mind. He received a vision of events on the spirit plane and he recorded a clear description of the Father just as the apostle John would, several centuries later.
We read earlier that Jesus later revealed in John 5:37 that even though God the Father is a spirit Being, He still has form and shape. Daniel also saw a multitude of loyal angelic beings, constantly serving the Father, who had a shape and form but in the spiritual realm.
We see the Ancient of Days, the One who became the Father, seated on a throne. He wore clothing. He has iridescent white hair. Then we see two God beings at the same place at the same time, and it is designated that the second one is the One who is going to bear rule in the kingdoms of men. We don't have to think very deeply to figure out who that second one was.