A t-test is a statistical method used to determine if there is a significant difference between the means of two groups. It helps researchers understand whether the differences observed in sample data are likely to reflect true differences in the larger population. The test calculates a t-value, which is then compared to a critical value from the t-distribution to assess significance. There are different types of t-tests, including the independent samples t-test, which compares two separate groups, and the paired samples t-test, which compares two related groups. By using a t-test, researchers can make informed decisions based on their data and draw conclusions about their hypotheses.