Although silicon (Si) is not yet listed among the essential elements for the growth of higher plants, it has been well documented to play an important role in providing benefi cial effects on growth and yield, especially in plants under stressful environments. From a practical perspective, the use of slag-based silicate fertilizers in agriculture can be dated back to the Middle Ages in Europe. Over the last decade, the discovery of specifi c Si transporters in rice roots has allowed great progress in the understanding of Si uptake by plants at the molecular level. In the same manner, important advancements have been made in dissecting the molecular mechanisms by which Si enhances plant resistance to fungal and bacterial diseases and insect pest damage. In contrast, more efforts are needed to explain at the molecular level the numerous reports showing Si benefi ts against abiotic stresses. In this chapter, a brief review is presented focusing on the most important historical points and general introduction of worldwide Si research.