Crying is when tears come out of a person's eyes because of their emotions
Some animals also cry. However, animals mostly release tears for reasons such as intense pain, and also cry when losing loved ones, seeing their own species being killed for their skin and meat, but these two reasons are mostly rare.[1]
When over 300 adults were asked how often they cried, they found out that men usually cry once every month, and women cry five or more times per month.[2]
According to the German Society of Ophthalmology, which has collected scientific studies on crying, the average woman cries between 30 and 64 times a year, and the average man cries between 6 and 17 times a year.[3]
A useful term is lachrymation, which means the non-emotional shedding of tears. There are many terms for the more usual crying: sobbing, weeping, wailing, whimpering, bawling, and blubbering.
In general, crying is non-verbal communication. It (and other) facial signals evolved in our species as ways which help people in social groups signal feelings. The term "a cry for help" recognises this function. "Cry for joy" expresses the fact that sometimes great delight can be the trigger for crying.