The given text snippets describe various t-test calculators and their functions. They mention the types of t-tests that can be performed, such as unpaired, paired, and Welch's t-tests, and the calculations that can be made such as P-values, confidence intervals, and effect sizes. Some of the calculators also include features such as identifying outliers, creating distribution charts and histograms, and conducting t-tests for two dependent samples. The tools can be used for statistical significance testing and to compare means of two data sets. Several of the calculators mentioned are online tools or videos that provide instructions on how to use them.