Formal:
* Editing: This is a general term for reviewing and correcting written work, including grammar.
* Proofreading: This focuses specifically on catching errors in grammar, spelling, and punctuation.
* Grammatical correction: This is a straightforward way to describe the act of fixing grammatical mistakes.
Informal:
* Grammar-nazi-ing: This is a humorous, but often derogatory, term for overly critical grammar correction.
* Nitpicking: This implies focusing on minor details, which can be seen as overly critical, even if the focus is on grammar.
* Pointing out errors: This is a neutral way to describe the act of identifying mistakes, though it can be perceived as critical.
The best way to describe it depends on the context and your relationship with the person whose grammar you are correcting. If you're working with someone on a professional project, "editing" or "proofreading" are the most appropriate terms. If you're having a casual conversation with a friend, you might use "grammar-nazi-ing" or "nitpicking" playfully, but be aware that these terms can be offensive to some people.