The Divergence Test is a method used in calculus to determine whether a series diverges. If the limit of the terms of a series, as the index approaches infinity, does not equal zero, then the series diverges. This means that the sum of the series does not converge to a finite value. For example, consider a series represented as Σ a_n. If the limit of a_n as n approaches infinity is not zero, then according to the Divergence Test, the series diverges. However, if the limit is zero, the test is inconclusive, and further analysis is needed to determine convergence or divergence.