Commas are optional
Opinions differ over whether to use a comma before a conjunction (“and” or “or”) that precedes the last item in a series
- German and English: You can open, close and save your file.
- English: You can open, close, and save your file.
- Use comma if confusing without it
- Confusing: My favorite combinations are green and yellow, blue and purple and black and red. Correct: My favorite combinations are green and yellow, blue and purple, and black and red.
- Confusing: I wanted to invite Juerg, Frank and Mathias and Claudia. Correct: I wanted to invite Juerg, Frank and Mathias, and Claudia.