Sigma (letter)

Sigma (Σ, σ) is the 18th letter of the Greek alphabet. In general knowledge, it has several uses: in mathematics, it represents the summation symbol, indicating the addition of a series of numbers. In statistics, it denotes standard deviation, which measures data variability. Additionally, in social contexts, "sigma" can refer to a personality archetype, often described as an independent thinker who operates outside traditional social hierarchies. Overall, sigma is significant in various fields, from mathematics and science to psychology and culture.