Gibberellins (GA) are a large group of tetracyclic diterpenoid carboxylic acids, which are essential for many processes in plants, including seed germination. In combination with other hormones, it helps the plant to overcome abiotic stress. The authors of this book examine the main issues regarding the production, functions and biosynthesis of gibberellins. The importance of the biosynthesis, deactivation and signaling of gibberellins are discussed as well. Additionally, current research on the prominent molecular mechanisms that control GA levels, and their physiological involvement in plant growth and metabolism are examined. The recent advances of the importance of GA modulating plant immunity and the positive and negative regulators signaling pathways crosstalk in disease and defense are looked at as well. The last chapter of this book is focused on the mechanisms involved in the control of tuberization by gibberellins, including the regulation of bioactive GA levels, the mechanisms of action during tuber formation, and the interaction between GA and other hormones affecting tuberization.