Accurate forecasts form the basis for a variety of economic decisions and business processes. This book explores the fundamentals of creating and quantitatively assessing forecasts. Special attention is given to the correct statistical treatment and the interpretation of forecasts as probability distributions. Numerous examples from specific questions illustrate the relevance of the discussed issues to practice. Additionally, many complementary methods are presented, showing how forecasts can be evaluated in practice and their predictive power tested. The book is primarily aimed at practitioners who use forecasts in their daily business operations and make data-driven automated decisions.