Expansion of the Universe: The fundamental premise that the universe is not static but expanding, with galaxies moving away from each other, as described by Hubble's Law.

Cosmic Microwave Background (CMB): The uniform background radiation detected across the sky, interpreted as the residual heat from the early, hot, dense universe, dating back to about 380,000 years after the Big Bang.

Big Bang Nucleosynthesis (BBN): Predicts the observed cosmic abundance of light elements (Hydrogen, Helium, Lithium) formed during the first few minutes after the Big Bang, which matches astronomical observations.

Initial Singularity: The theory posits that the universe began from an extremely hot and dense point, though it does not describe the singularity itself.

Inflationary Epoch: A brief period of extremely rapid, exponential expansion shortly after the Big Bang (10^-36 to 10^-32 seconds), proposed to solve the horizon and flatness problems of the standard Big Bang model.

Age of the Universe: Based on the Big Bang model and observational data, the universe is estimated to be approximately 13.8 billion years old.

Evolutionary Stages: Describes the universe's evolution through various epochs, including the Planck epoch, Grand Unification epoch, Electroweak epoch, Quark epoch, Hadron epoch, Lepton epoch, Nucleosynthesis, Recombination, Dark Ages, and Reionization.

Formation of Structure: Explains how small density fluctuations in the early universe, amplified by gravity (and dark matter), led to the formation of galaxies and large-scale cosmic structures.

Standard Model of Cosmology (Lambda-CDM): The current standard model that incorporates the Big Bang theory along with the existence of dark matter and dark energy to explain the universe's composition and evolution.

Expansion of the Universe: The fundamental premise that the universe is not static but expanding, with galaxies moving away from each other, as described by Hubble's Law.

Cosmic Microwave Background (CMB): The uniform background radiation detected across the sky, interpreted as the residual heat from the early, hot, dense universe, dating back to about 380,000 years after the Big Bang.

Big Bang Nucleosynthesis (BBN): Predicts the observed cosmic abundance of light elements (Hydrogen, Helium, Lithium) formed during the first few minutes after the Big Bang, which matches astronomical observations.

Initial Singularity: The theory posits that the universe began from an extremely hot and dense point, though it does not describe the singularity itself.

Inflationary Epoch: A brief period of extremely rapid, exponential expansion shortly after the Big Bang (10^-36 to 10^-32 seconds), proposed to solve the horizon and flatness problems of the standard Big Bang model.

Age of the Universe: Based on the Big Bang model and observational data, the universe is estimated to be approximately 13.8 billion years old.

Evolutionary Stages: Describes the universe's evolution through various epochs, including the Planck epoch, Grand Unification epoch, Electroweak epoch, Quark epoch, Hadron epoch, Lepton epoch, Nucleosynthesis, Recombination, Dark Ages, and Reionization.

Formation of Structure: Explains how small density fluctuations in the early universe, amplified by gravity (and dark matter), led to the formation of galaxies and large-scale cosmic structures.

Standard Model of Cosmology (Lambda-CDM): The current standard model that incorporates the Big Bang theory along with the existence of dark matter and dark energy to explain the universe's composition and evolution.