In order to achieve better weed control, it is necessary to understand the biology of weeds and their population dynamics within agroecosystems. The use of herbicides requires a basic knowledge of their chemistry, their effects, and their application in order to justify their usage and to achieve optimal results, whilst at the same time attempting to reduce their toxicological effects on both humans and the environment. Additionally, certain statistical knowledge, necessary for proper data analysis, appropriate experimental design and sampling methods, is vital for efficient decision-making procedures. Since weed science is an important part of integrated crop management, an understanding of various agronomic procedures is also essential. It follows, therefore, that a weed scientist must be knowledgeable in many aspects of the agricultural, biological, and analytical sciences in order to make decisions, sometimes quickly, which are not merely feasible but also optimal. The Encyclopaedic Dictionary of Weed Science: Theory and Digest provides essential, easily accessible information in a user-friendly format enhanced, where necessary, with many tables, graphs, pictures, or figures, in as compact a way as possible.