Here's a breakdown:
When run-on sentences are NOT acceptable:
* Formal writing: Academic essays, reports, professional documents, etc. These require clarity and precision, and run-on sentences can make your writing confusing and difficult to understand.
* When clarity is paramount: If your goal is to communicate information effectively, run-on sentences can hinder that.
When run-on sentences CAN be acceptable:
* Informal writing: Creative writing, personal essays, dialogue, etc. Run-on sentences can:
* Mimic natural speech: People don't always speak in perfectly punctuated sentences. Run-ons can make dialogue sound more realistic.
* Create a sense of urgency or excitement: A rapid flow of words can convey a sense of immediacy.
* Emphasize a particular point: By merging two closely related clauses, you can draw attention to their connection.
* Literary effect: Some authors use run-on sentences deliberately to create a specific effect, like mirroring a character's stream of consciousness or creating a feeling of chaos.
However, even in these cases, it's crucial to use run-on sentences judiciously. Too many run-ons can be jarring and make your writing difficult to read.
Remember:
* Even in informal writing, it's generally best to use run-on sentences sparingly.
* If you're unsure whether a sentence is a run-on, it's best to break it up.
* Proofread carefully and consider the impact of your sentence structure on your writing.
If you're unsure about using run-on sentences, it's always best to err on the side of caution and use proper sentence structure.