* Common noun: It refers to a general category of something, in this case, a raised platform used for performances.
* Concrete noun: It refers to something that is physical and tangible. You can see and touch a stage.
The specific type of "stage" you are referring to will determine its exact noun classification. For example, if you are talking about a specific stage in a theater, it could also be considered a proper noun (e.g., "The Majestic Stage").