The Upnishads are the part of the Vedas related to God realization and the path to God. Attaining God is the ultimate purpose of life as defined by Hindu philosophy. Thus, the Upnishads are the culmination of the Vedic knowledge. There are 1,180 branches of the four Vedas: the Rigved contains 21 branches, the Samved 1,000, the Yajurved 109, and the Atharvaved 50. There is one Upnishad for each branch of the Vedas; thus, there are 1,180 Upnishads in total.
The spiritual knowledge of the Upnishads is extensive and is in difficult Sanskrit. Thus, to condense that knowledge and make it more easily understandable, Shree Krishna produced it in the form of the Bhagwad Gita. It is said that if the Upnishads are cows, then Shree Krishna milked those cows, and the milk is the Gita. The Gita contains the entire knowledge of the Upnishads in only 700 shlokas, so it is the essence of the Upnishads. In fact, the Gita is regarded as having the same status as an Upnishad, so it is also known as the Gitopnishad (Gita + Upnishad = Gitopnishad).
Because the prime subject matter of the Gita relates to finding God, it is also called Brahm Vidya Shastra, which means the scripture containing the knowledge of God. However, this does not mean that simply by reading the Gita you can know God. It means that if you practice the teachings of the Gita, then you can know God.
In the next part of this series, before delving into the actual teachings of the Gita, I will address a few more questions regarding its origins and antiquity.