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Deriving the Normal Distribution's PDF, Mean, and Variance in Probability

In probability theory, the normal (Gaussian) distribution is defined by a symmetric bell-shaped probability density function characterized by two parameters, mean and variance, with the standard normal N(0,1) given by a specific exponential form whose normalizing constant, mean, and variance are derived analytically using properties of odd/even functions, polar-coordinate transformation of a squared integral, and integration by parts (via the law of the unconscious statistician). The distribution's centrality in statistics stems from the central limit theorem, which states that the sum of a large number of i.i.d. random variables converges in distribution to a normal distribution regardless of the individual variables' underlying distribution.