Ever wonder why water comes out of our eyes when we are sad or tired or frustrated? Turns out that crying is one of the most unique and complicated featureof human behaviors. It is the only thing that is unique to humans. And the tears themselves are complex–we actually shed three different kinds of tears.We can cry because we are happy. We can cry because we're sad. We can cry because we're cutting onions. We can cry just because we need to cry. They are all completely different emotions. Types of Tears - 1.) Basal Tears:- The cornea is continually kept wet and nourished by basal tears. They lubricate the eye, and help to keep eye clear of dust.These tears are chemically different from other type of tears. Characteristics: • Keep dirt away. 2.) Reflex Tears:- The second type of tears results from irritation of the eye by foreign particles, or from the presence of irritant substances such as onion vapors, perfumes and other fragrances, tear gas, or pepper spray. Characteristics of reflex tears: • Wash away harmful substances • Released in large amounts • Aqueous layer contains antibodies to stop microorganisms 3.) Emotional Tears or Psychic Tears:- This type of tears are unique to humans is the most mysterious kind of tears. Crying or weeping, is increased tearing due to strong emotional stress, pleasure, anger, suffering, mourning, or physical pain. This practice is not only restricted to negative emotions; many people cry when they are extremely happy. There is also the argument that a good cry reduces stress. Also tears help build strong communities by evoking empathy and closer relationships necessary to living in a complex society. Characteristics of emotional tears: • Stabilize mood. • Contains higher level of stress such as ACTH and encephalin – Natural pain killer. Now the next time you are watching a sad scene in a movie, you will know that your eyes are producing tears for a purpose and can reflect on how the tears are an example of the system that make us humans .