Introduction.- Definitions.- Units, Fundamental Constants and Conversion Factors.- General Considerations.- Electronic Stopping of Point Charges.- Electronic Stopping of Dressed Ions.- Aggregation Effects.- Low-Velocity Electronic Stopping.- Survey of Current Theoretical Schemes.- Nuclear Stopping.- Related Processes.- Statistics of Particle Penetration.- Straggling.- Multiple Scattering.- Restricted Nuclear Stopping.- Range and Range Straggling.- Concluding Remarks.