The Big Bang theory postulates that the universe originated from an incredibly hot and dense singularity around 13.8 billion years ago. It explains the expansion and evolution of the universe through the concept of cosmic inflation. According to this theory, the universe expanded rapidly in the first moments after the Big Bang, cooling down and allowing matter and energy to form. Over time, these particles coalesced to form stars, galaxies, and larger cosmic structures, leading to the diverse and vast universe we see today.
