I’d say it’s closer to a character style. Moe is a term that originally referred to the soft warm feeling you get when you view a cute character. Like the feeling of wanting to protect them eg Rosa from Brooklyn 99’s reaction to holding a puppy.

Nowadays I’d say it’s also a way to get more views for your middling anime. Eg the trope of cute girls doing some random hobby. Popular examples of the trope include lucky star, nichijou, the one about the euphonium that I can’t remember the full name of, and plenty more that are terrible that I never bothered to watch or remember their name. The trope isn’t necessarily bad, as the named examples above are good shows, but it is often used to try to draw viewers to bad anime by including token, or entirely filled with Moe characters.

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