Thermal runaway is a condition where an increase in temperature leads to further increases in temperature, often resulting in a destructive cycle. This phenomenon commonly occurs in batteries, such as lithium-ion batteries, where excessive heat can cause chemical reactions that generate even more heat. If not controlled, this can lead to fires or explosions. In electronic devices, thermal runaway can happen when components overheat due to poor ventilation or excessive current. Proper design and safety measures, like thermal management systems, are essential to prevent this dangerous situation and ensure the safe operation of devices like smartphones and electric vehicles.