What was the big bany theory?

The Big Bang Theory is the leading scientific explanation for the origin of the universe, positing that it began approximately 13.8 billion years ago from an extremely hot and dense singularity. This event initiated the expansion of space, leading to the formation of galaxies, stars, and other cosmic structures over time. Evidence supporting the theory includes the cosmic microwave background radiation and the observed redshift of distant galaxies, indicating that the universe is still expanding. The theory also provides a framework for understanding the evolution of the universe and its physical laws.