A Chi-square test is a statistical method used to determine if there is a significant association between categorical variables. It compares the observed frequencies of events in different categories to the frequencies expected if there were no association. This helps researchers understand whether the differences in data are due to chance or if they indicate a real relationship. There are two main types of Chi-square tests: the Chi-square test of independence, which assesses whether two categorical variables are related, and the Chi-square goodness-of-fit test, which checks if a sample distribution matches an expected distribution. Both tests are widely used in fields like social sciences and health research.