Tears are clear liquid made by the body to clean and lubricate the eyes.
There are three different types of tears that the body makes:
Basal tears: In a normal, healthy mammal, tears are regularly made to clean the cornea (front part of the eye) and to keep it clean from dust.
Reflex tears: This type of tear is made when something irritates the eye, say, bits of dust or the smell of an onion. These tears are made to clean the eye and wash out anything irritating it.
Emotional tears (psychic tears): The last category is called crying or weeping, when tears are made because of physical pain or strong emotions.