This document discusses numerical methods and their applications. It begins by defining numerical methods as approaches for solving complex mathematical problems using simple arithmetic operations. Numerical methods are needed because many models cannot be solved analytically or the analytic solution is too costly. The key steps in solving a problem numerically are formulating the mathematical model, constructing an appropriate numerical method, implementing the method, obtaining a solution, and validating the solution. Engineering applications of numerical methods include modeling mechanical systems, analyzing structural loads and vibrations, and simulating processes like combustion and spacecraft re-entry. Everyday applications include modeling airflow over airplanes, estimating ocean currents, analyzing shock waves, and fitting curves to tabular data like in electromagnetics simulations.