1. Basics of collisions. 2. Motion of a free micro-particle. 3. Collision of a free particle with a potential field. 4. Collision of electrons with a potential. 5. Collision between two particles. 6. Collision of photons with atoms. 7. Collision of electrons with atoms: the integral approach. 8. Collision of electrons with atoms: the differential approach. 9. Collision of electrons with molecules. Questions and Prolems. References. Subject Index.