Copy is a broad term referring to the written word generated in any number of contexts for a variety of purposes. In advertising, copy intends to sell a product by convincing consumers they can’t live without it.
Copy can describe a series of steps toward a goal, like how to make and use a homemade version of the lye that turns the crust on a bagel all crispy and brown. Or the text can provide details about a moment in history such as when a dam washes away. And then washes away again. And then they rebuild it. In the same place.
The tone of voice can be formal or informal, conversational or educational. The writer can be named or a piece can be ghostwritten.
Publication can take place on the web, in a brochure or flyer, or take the form of a white paper intended for broad or narrow distribution.