This lecture covers the basics of thermonuclear fusion, discussing the case for fusion energy, fusion reactions, advantages of fusion, plasma physics, and fusion fuels. It explains how fusion is the energy source of stars, the D-T reaction, and the importance of plasma physics in fusion energy research. The lecture also explores the concept of thermonuclear fusion, fusion reactor schematics, and the advantages of fusion such as high energy density, practically inexhaustible fuels, and environmental benefits.