What is "fine-tuned universe"

n. A universe whose parameters (fundamental constants) are within a very narrow range enabling chemically based life to exist.

The fine-tuned Universe is the proposition that the conditions that allow life in the Universe can only occur when certain universal fundamental physical constants lie within a very narrow range, so that if any of several fundamental constants were only slightly different, the Universe would be unlikely to be conducive to the establishment and development of matter, astronomical structures, elemental diversity, or life as it is understood. The possible explanations for fine-tuning are discussed among philosophers, scientists, theologians, and proponents and detractors of creationism. The fine-tuned Universe observation is closely related to, but is not exactly synonymous to, the anthropic principle, which is often used as an explanation of the observation.