Common Noun:
* When "party" refers to a general gathering of people, it is a common noun.
* Example: "We had a fun party last night."
Proper Noun:
* When "party" refers to the name of a specific group, it becomes a proper noun and should be capitalized.
* Example: "The Democratic Party is one of the two major political parties in the United States."
* Example: "The Green Party advocates for environmental protection."
Key Takeaway:
The grammatical status of "party" hinges on whether it's referring to a general concept or a specific named entity.