Tree-ring data is a type of dendrochronology or the study of tree rings to determine past climate conditions, environmental changes, and historical events. Each year, trees form a new ring in their trunk or branches, and the width, density, and composition of these rings can provide valuable information about the tree's growth patterns and the external conditions that influenced it. Tree-ring data is often used by scientists to reconstruct climate history, dating back hundreds or even thousands of years, by analyzing patterns in the tree rings. This information can help researchers understand past climate variations, droughts, floods, and other environmental changes, as well as inform future climate and conservation efforts.