We don’t really think about tears until they overflow and roll down the sides of our cheeks whilst we brush them away. These tears can be the onset of sadness, happiness, or tiredness, but why do we cry in the first place? In the TED Ed video, "Why Do We Cry? The Three Types of Tears," Alex Gendler explains the physiology of tears through their three classifications: basal, reflex, and emotional.

Crying is so innate, we produce 10 ounces per day and 30 gallons a year. When it comes to gender, it seems more women compared to men are shedding tears. Women cry an average of 5.3 times a month, while men cry an average of 1.3 times per month, according to a 2011 study published in the Journal of Research in Personality. Researchers believe this is because women are biologically wired to shed more tears than men, since female tear glands are much smaller than men’s.

Regardless of gender, we actually all cry every second of our lives and produce the same types of tears. The lacrimal gland, located in the outer part of the upper eye, is constantly secreting a protein-rich, antibacterial liquid. This fluid goes from the outer edge of the eyeball toward the cornea and lubricates the entire eye surface every time we blink.

The crying we are all familiar with is when excess liquid overwhelms the drains of the nasal canal of the tear duct, which overflows and falls down our cheeks. Basal tears are always in our eyes to serve the purpose of lubricating, nourishing, and protecting the eyes. The second type of tears, known as reflex tears, protect the eyes from irritants, including wind, smoke, or onions. Lastly, the third type are those that are produced by emotion. Although these tears contain higher levels of stress, such as ACTH and enkephalin — an endorphin and natural pain killer — they can also work by directly calming the iris down while signaling the emotional state to others.

We’ve been crying since we were babies and will continue to do so for the rest of our lives, so even if we don’t always know why we're cry, it's nice to know the intricacies.