A Parameterized test is a test where the inputs and outputs are not fixed. That is, you can pass different parameters into the same test method and get different results. This is especially useful when you want to test the same method with different data sets. For example, let's say you have a method that calculates the average of an array of integers. You could write a Parameterized test to pass in different arrays of integers and check that the method returns the correct average each time. To create a Parameterized test, you first need to create a class that extends from the junit.framework.TestCase class. Then, you need to annotate the class with @RunWith(Parameterized.class). Finally, you need to create a public static method that returns a Collection of Object[] arrays. Each Object[] array corresponds to a set of input parameters that will be passed into the test method. The test method must be annotated with @Parameters, and it must take an array of objects as its parameter. When the Parameterized test is run, JUnit will invoke the test method once for each set of input parameters. That is, if your Collection contains three Object[] arrays, JUnit will invoke the test method three times, passing in each array as the parameter. You can then use assertions to check that the output of the method is what you expect it to be. Parameterized tests are an extremely powerful way to increase the coverage of your unit tests. Bypassing fixed inputs and outputs lets you exercise different code paths within your methods and get a better sense of how they will behave in different situations.