This sentence, despite its ridiculous length and all the useless things it has to say, with its added phrases and clauses that have no content and give you nothing but extra words, that feels like it should be a run on because it’s so freaking long and is as boring as a sentence is allowed to be—even though it’s a little ironically funny in that it keeps babbling while saying nothing—and maybe makes you feel like pulling out your hair, is not a run on sentence and is one hundred percent grammatically correct. This sentence is incorrect it is a run on.
This sentence is also incorrect, it is also a run on.
Really? ‘Tis true. The first sentence is a run on because it is two complete sentences put together with no conjunction, no semi-colon, no period—nothing to indicate the end of a sentence.
The second sentence is a special (and annoyingly common) run on called a comma splice: two sentences “spliced” together with a comma.
Because here’s the thing: “run-on” doesn’t mean long; it means you’ve got two sentences you smashed together, even if they are two tiny sentences.

