In the first Gremlins movie Gizmo, a Mogwai and the host for the later gremlins, is in the care of an elderly Chinese man who sells various trinkets from the Orient in his small shop in Chinatown, New York. The Chinaman's son sells Gizmo to an inventer who gives him to his son Billy Peltzer (Zach Galligan) as a Christmas gift. There are 3 rules for taking care of a Mogwai: #1 Don't let them be exposed to bright light, especially sunlight which kills them, #2 Don't get them wet (or else they spawn additional mischevious Mogwai), and #3 Don't feed them after midnight (or else they morph into large green violent gremlins). Also, if a Mogwai has already turned into a Gremlin, and it is then splahsed with water, it will spawn additional Gremlins, instead of Mogwai. The natural language of the Mogwai appears to be that of singing various tones. They are fast learners (like a Ferby) and pick up human language quickly, but are even faster at learning how things work - which is what makes a gremlin so dangerous to a technology dependent world.
Opening The Stargate via Gremlins - The Stygian Port
Gremlins - IMDB.com
Gremlins 2: The New batch - IMDB.com