Reduction in size often does more than simply make things smaller. There are many properties of materials that undergo qualitative, often sudden, changes below a certain size scale. This Report first describes some of these size-dependent properties. Following this general description, recent developments in a number of selected topics in nanoscience are covered. These topics are: luminescence from Au nanoparticles; Si (and related) nanoparticle luminescence; modification of optical absorption by surface adsorption on nanoparticles; and transistors (and some other devices) based on nanotubes and nanowires.