The Comparison Test is a method used in calculus to determine the convergence or divergence of infinite series. It involves comparing a given series with a known benchmark series. If the series being tested is smaller than a convergent series, it also converges. Conversely, if it is larger than a divergent series, it diverges. This test is particularly useful when dealing with series that are difficult to analyze directly. By selecting appropriate benchmark series, such as the p-series or geometric series, one can easily conclude the behavior of the series in question, simplifying the process of convergence analysis.