Convergence is a mathematical concept referring to a sequence or series approaching a specific limit as more terms are added. There are different types of convergence such as absolute and conditional. Convergence criteria like the Cauchy criterion and Bolzano-Weierstrass theorem can determine if a sequence converges. Convergence plays a crucial role in algorithms, numerical methods, and fields like physics by ensuring solutions continuously approach the true value. Assessing convergence properties is essential for evaluating algorithm efficiency and accuracy of numerical solutions.