Heat exhaustion is a condition that occurs when the body loses too much water and salt, often due to excessive sweating in hot weather. Symptoms include heavy sweating, weakness, dizziness, nausea, and headache. It can affect anyone, especially those engaged in strenuous activities or those who are not acclimated to high temperatures. If not treated promptly, heat exhaustion can lead to more severe conditions like heat stroke, which is a medical emergency. To prevent heat exhaustion, it is important to stay hydrated, take breaks in the shade, and wear lightweight clothing during hot weather.