Flirting

Why does she say hello to me when I have practically never started talked with her?

There is this girl I hardly ever talk to but sometimes she comes and says hello to me. She ALWAYS comes and says hello and asks how are you to me whenever I'm not with my friends and she isn't with hers. Another thing I noticed was that she was smiling the entire time she was talking to me (but then again she smiles whenever she talks to anybody unless she's asking a question about something like schoolwork). The thing that surprises me is that she isn't an extrovert and is more of a shy person and yet she tries to talk to me when I have hardly ever talked to her. She is smart and kind but isn't spontaneous or loud (would NEVER do anything to attract attention to herself in public). she is also quiet and if she has to talk to somebody, she would talk about stuff they want to talk about. She also only has one guy friend and the rest of her friends are girls. So what do you think is going on?
Why does she say hello to me when I have practically never started talked with her?
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