Standard Cosmological Model

Relies on Einstein's theory of General Relativity and describes the Universe on the largest scales.
Needs as input:
The current expansion rate
The amounts of the various "types of stuff" in the Universe.
The lumpiness of that stuff a small fraction of a second after the big bang.
Physics during the plasma phase (first 300,000 years) was very simple.
Given input above theory confidently predicts the expected lumpiness of the CMB pattern
Measure the pattern - work backwards  - find out what the Universe is made out of and its history and fate!