What is moe anthropomorphism(-tans)?
Moe anthropomorphism (萌え擬人化 moe gijinka?) is a form of anthropomorphism where moe qualities are given to non-human beings, objects, concepts, or phenomena. In addition to moe features, moe anthropomorphisms are also characterized by their accessories, which serve to emphasize their original forms before anthropomorphosis. The female character here, usually in a kind of cosplay, is drawn to represent an inanimate object or popular consumer product, since females often have curvier body lines than males. Part of the humor of this personification comes from the personality ascribed to the character (often satirical) and the sheer arbitrariness of identifying a variety of machines, objects, and even physical places as cute.
Many names of these girls end with -tan (たん), which is a child's mispronunciation of -chan (ちゃん), an informal, intimate, and diminutive honorific suffix for a person used for friends, family, and pets. In this case, the mispronunciation is used intentionally to achieve the contrived cute or charming effect that is commonly associated with its use by young children. -taken from wikipedia