This is an overview of particulate filler production and use. Each filler type has different properties and these in turn are influenced by the particle size, shape and surface chemistry. Filler characteristics are discussed from costs to particle morphology. Practical aspects of filler grading are described and the principal filler types are outlined. Filler surface modification is an important topic. The main types of modifying agent and their uses are described, from fatty acids to functionalised polymers. An additional indexed section containing several hundred abstracts from the Rapra Polymer Library database gives useful references for further reading.