This lecture covers the fundamentals of electron diffraction, including topics such as diffraction theory, crystallography, symmetry, and the reciprocal lattice. It explores the use of electron diffraction in studying crystal structures, symmetry relationships, and twinning phenomena. The presentation also delves into advanced techniques like convergent beam electron diffraction and the interpretation of diffraction patterns. Practical applications of electron diffraction in materials science and nanotechnology are discussed, highlighting its importance in characterizing crystal structures and interfaces.