A run-on sentence is a term for an unfinished sentence in the English language. The word run-on is itself an example of a run-on sentence, being both a run-on from a sentence and a run-on sentence.
A run-on sentence arises when two independent clauses are joined without the use of suitable punctuation or conjunctions. See the following example:
Jack sings upbeat children’s songs he is a great musician. – Incorrect
Jack sings upbeat children’s songs; he is a great musician. – Correct
Run-on sentences are often found in informal written English. A run-on sentence may be thought of as a “jumble of clauses” with no syntactic or semantic relation to each other.
A run-on sentence has no internal structure and is usually used for stylistic effects (e.g., rhetorical effects) rather than for clear exposition. Run-on sentences are considered to be bad or incorrect in style in formal written English.