This document discusses improper integrals, which are integrals with infinite limits of integration or an integrand that is unbounded within the limits. There are four types of improper integrals: 1) when the upper limit is infinity, 2) when the lower limit is infinity, 3) when both limits are infinity, and 4) when the integral is unbounded. The document provides examples of each type and explains that an improper integral converges if the limit exists as the limiting value is approached, and diverges if the limit does not exist. Tests for convergence like the p-integral test are also mentioned.