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Run-on Error
What Is a Run-On Error?
A run-on error is a common writing mistake caused by using inappropriate punctuation at the end of a sentence. Most run-on errors involve writers putting a comma at the end of a sentence and then writing another closely related sentence.Once you have written a sentence, you must end it with appropriate punctuation such as a period (full stop), an exclamation mark, or a question mark (if it's a question). You cannot put a comma and write another sentence. This is the most common mistake involving commas. It is called a run-on error.
An example of a run-on error:
- I like clowns, they can be scary though.
- I like clowns. They can be scary though.
- I like clowns; they can be scary though.
- I like clowns — they can be scary though.
- I like clowns ... they can be scary though.
A sentence can also end in a question mark (?), or an exclamation mark (!). If we're being really pedantic, it could also end in a speech mark (provided there's a period, question mark, or exclamation mark inside), but it definitely can't end in a comma.

Examples of Run-On Errors
Here are some more examples of run-on errors:- Pick up a copy of our free brochure, this explains how to contact us and reach our showroom.
- It's not true that I had nothing on, I had the radio on.
(Actress Marilyn Monroe)
- Only one man in a thousand is a leader of men, the other 999 follow women.
(Comedian Groucho Marx)
- Be kind to those that meet you as you rise, you may pass them again as you fall.
- This suspense is terrible, I hope it will last.
(Playwright Oscar Wilde)
- Duty is what one expects from others, it is not what one does oneself.
(Playwright Oscar Wilde)
- When will I learn? The answers to life's problems aren't at the bottom of a bottle, they're on TV.
(Homer Simpson)
Examples of Sentences without Run-On Errors
The trick to avoiding the run-on error is to keep your discipline with what constitutes a sentence. Here are some examples of sentences that too many people would reproduce with run-on errors.- I always pass on good advice. It is the only thing to do with it. It is never of any use to oneself.
(Irish poet Oscar Wilde)
- Please don't eat me! I have a wife and kids. Eat them!
(Homer Simpson)
- Please do not shoot the pianist. He is doing his best.
(Playwright Oscar Wilde)
- Drink is the curse of the land. It makes you fight with your neighbor. It makes you shoot at your landlord, and it makes you miss him.
- Age is not a particularly interesting subject. Anyone can get old. All you have to do is live long enough.
(Groucho Marx)
Why Is the Run-on Error So Common?
Writers often feel that a comma is more appropriate than a period (full stop) because their sentences are so closely related. In other words, they sense that a period is too abrupt because they haven't finished expressing their idea. Once you have formed a sentence (i.e., expressed a complete concept), you must put a period or another valid ending (like ! or ?). Do not insert a comma and continue writing. This is a common mistake.Other Options
Occasionally, it may be appropriate to use a semicolon, a dash, or three dots (ellipsis) to extend a sentence instead of putting a period and writing a second sentence. For example:- Duty is what one expects from others; it is not what one does oneself.
- Please do not shoot the pianist — he is doing his best.
- The answers to life's problems aren't at the bottom of a bottle ... they're on TV.
- Remember that a sentence is a grammatically complete series of words. Often, it will take several sentences to complete your idea. You can't just put a comma and carry on writing.
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