2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/72165We give an informal introduction to the most basic techniques used to evaluate moments on the critical line of the Riemann zeta-function and to find asymptotics for sums of arithmetic functions.11 pages, to appear in the proceedings of the school ``Recent Perspectives in Random Matrix Theory and Number Theory'' held at the Isaac Newton Institute, April 2004. Added appendix on big-O and << notationNumber Theory11M26text