Beryllium is a chemical element with the symbol Be and atomic number 4. It is a hard, greyish-white metal that is very lightweight and has a high melting point. Beryllium is used in a variety of industries, including aerospace, automotive, defense, and electronics, because it is strong, lightweight, and has good thermal conductivity. It is also used as a neutron reflector in nuclear weapons and reactors.

However, beryllium can pose a serious health hazard if it is not handled properly. Beryllium dust or fumes can be toxic, leading to respiratory and skin problems for those who are exposed to it. Chronic beryllium disease (CBD) is a serious illness that affects the lungs and can cause difficulty breathing, fatigue, and weight loss. To avoid these health risks, proper safety precautions should be taken when handling beryllium.