This chapter highlights the crucial role of sulfur in various volcanic processes, its challenges in study, and the subsequent environmental and climate impacts. Important topics covered are sulfur sources, solubility, hydrothermal reactions, monitoring emissions, and the non-linear relationship between sulfur output and climate impacts on Earth. The release of volcanic sulfur can harm ecosystems and infrastructure and cause health risks. Sulfur in the stratosphere can lead to cooling and alter atmospheric circulation. To gain a deeper understanding of the complex behavior of sulfur during volcanic eruptions, further research is essential.