Tears are salty because they contain dissolved salts, primarily sodium chloride, which is the chemical name for common salt. The salinity of tears comes from the composition of the fluids and tissues in and around the eyes.

The tear fluid is produced by glands located around the eye, including the lacrimal gland. This fluid is a mixture of water, proteins, antibodies, oils, and electrolytes, which include sodium and chloride ions. These ions are essential for maintaining the proper balance of fluids in and around the eye and for supporting the antimicrobial properties of tears.

The human body contains a certain concentration of salt in its fluids to maintain homeostasis. When tears are secreted, they carry a proportionate amount of these salts from the surrounding tissues. When tears are shed, they evaporate, leaving behind the dissolved salts, which is why they taste salty if they’re licked off the cheek or why dried tears can sometimes leave a crusty residue.

So, tears are salty because they reflect the natural salt content found in the body’s extracellular fluid and because the process of tear production incorporates these salts as part of the necessary composition for the eye’s health and function.