Here's why:
* Common nouns refer to general, everyday things, not specific individuals or places. "Gift" is a general term for something given freely.
* Proper nouns are specific names (e.g., John, London, Christmas).
* Abstract nouns represent ideas, qualities, or concepts (e.g., love, happiness, freedom). While "gift" can represent an idea of generosity, it also has a concrete, physical aspect.
Let me know if you have other words you'd like to categorize!