Chemical compounds are substances formed when two or more different elements chemically bond together. These bonds can be ionic, where electrons are transferred, or covalent, where electrons are shared. Common examples include water (H₂O), which consists of hydrogen and oxygen, and table salt (NaCl), made from sodium and chlorine. Compounds can have very different properties from the elements that compose them. For instance, while sodium is a highly reactive metal and chlorine is a toxic gas, their compound sodium chloride is safe to consume. Understanding chemical compounds is essential in fields like chemistry, biology, and medicine.