The Chi-square distribution is a statistical distribution commonly used in hypothesis testing, particularly in tests of independence and goodness-of-fit. It is defined by its degrees of freedom, which are determined by the number of categories or variables involved in the analysis. The distribution is positively skewed, meaning it has a longer tail on the right side. In practical applications, the Chi-square distribution helps researchers determine whether observed data significantly differ from expected data. It is widely used in fields such as social sciences, biology, and market research to analyze categorical data and assess relationships between variables.