This technical note introduces Maximum Power Point Tracking (MPPT), a family of control algorithms that maximizes power drawn from sources with fluctuating output, such as PV panels and wind turbines. It explains why the maximum power point must be continuously tracked, illustrates the concept with a PV panel's power-voltage curve, and focuses on the Perturb and Observe (P&O) algorithm, including its requirements and multi-rate implementation. It then provides practical guidance and downloadable resources for implementing P&O MPPT in Simulink, PLECS, and C/C++.