One typical use of inferential statistics is to test the likelihood that the difference between the means of two groups is due to chance. Several situations call for this sort of analysis, but they each use the approach that’s usually termed the t-test.
You’ll find as many reasons to run t-tests as you have outcomes to contrast. For example, in different disciplines you might want to make these comparisons:
Business—The mean profit margins of two product lines
Medicine—The effects of different cardiovascular exercise ...