1. When "Co" is part of a company name:
* No comma: If "Co" is part of the official company name, like "Google LLC," "Microsoft Corp," or "Apple Inc," you don't use a comma after "Co."
* Comma: If "Co" is used as a short form of "Company" and the company name is followed by a location, then you do use a comma after "Co." For example: "Acme Co., New York."
2. When "Co" stands for "Company":
* No comma: If "Co" is used as a general abbreviation for "Company," you don't use a comma after "Co." For example: "The Co. will be releasing its annual report next week."
Example:
* Correct: Google LLC is a multinational technology company.
* Correct: Acme Co., New York, is a leading manufacturer of widgets.
* Correct: The Co. will be holding a meeting to discuss the new product line.
In short: If "Co" is part of the official company name, no comma is needed. If it's a short form for "Company" and a location follows, then a comma is used. If it's used as a general abbreviation, no comma is used.