And Moses said unto God, Behold, when I come unto the children of Israel, and shall say unto them, The God of your fathers hath sent me unto you; and they shall say to me, What is his name? what shall I say unto them? And God said unto Moses, I Am That I Am: and he said, Thus shalt thou say unto the children of Israel, I Am hath sent me unto you. (Ex.3:13,14)
This is the Name by which only God can introduce Himself.
If somebody asked me who I am, I might answer by telling that I am the son of so and so, or that my profession is such and such, or that I work at such and such, etc. My identity is dependent on a host of other things. The technical term is "contingency". My identity is contingent upon a number of other factors.
However, God's identity is not dependent on anything else. He is who He is! As Ravi Zacharias said, "God is the only being in existence, the reason for whose existence lies within himself." God's identity is absolute, independent, and final - He is the Beginning and End of all things. In the ultimate sense, in fact, it is from Him that all things derive their particular identity.
"For in him we live and move and have our being." (Acts 17:28)
He is self-sufficient, self-contained, and self-satisfied eternally - in need of nothing. He is the great I AM!