1. Run-Ons and Comma Splices
Pasco Hernando Community College
Tutorial Series

2. What is a run-on?
While a fragment is something less than a sentence, a run-on is something more.  They are called run-ons since without end punctuation, the sentence runs on.   
Generally, the term run-on refers to the situation where there is no punctuation between sentences.   

3. What is a run-on?
A comma splice occurs when there is a comma between two sentences.  
A comma splice is a type of run-on since a comma is not end punctuation and cannot stop the sentence from running on even though comma splices are defined as a separate category.

4. Types of run-ons Fused run-ons:
Many people have seen the movie Titanic few of them have read the book.  (incorrect)
There are two sentences with no punctuation between them:
Many people have seen the move Titanic.
Few of them have read the cook.
These are called run-ons, fused run-ons, or fused sentence run-ons.

5. Types of run-ons Comma Splice run-on:
Sometimes, a comma is inserted between two sentences that are closely related, but this is also incorrect.
Many people have seen the movie Titanic, few of them have read the book.  (incorrect)
This is known as a comma splice run-on since the sentences are spliced together with the comma.  While it may be more clear than no punctuation, using a comma still does not properly separate the thoughts.

6. Fixing a run-on Periods Sentences must end with end punctuation
End of sentence punctuation includes periods, question marks, and exclamation points
Run-ons can be fixed by using a period. 
Many people have seen the movie Titanic few have read the book. (fused run-on)
Many people have seen the movie Titanic. Few have read the book. (corrected with a period)

7. Fixing a run-on
A semicolon (a blend of a comma and a period - ; ) may be used to separate short sentences so closely related they seem to belong in one sentence. 
Many people have seen the movie Titanic few of them have read the book. (fused run-on)
Many people have seen the movie Titanic, few of them have read the book. (comma splice run-on)
Many people have seen the movie Titanic; few of them have read the book. (corrected with a semicolon)
Note: Semicolons are not the equivalent of periods.  A semicolon should not be used often and should only be used when the sentences are short and when they are very closely related.

8. Fixing a run-on
Words such as also, consequently, furthermore, however, then, or therefore) are sometimes used between sentences.  These are called conjunctive adverbs. There still, however, must be a semicolon or period to separate the sentence.
Incorrect: Many people have seen the movie Titanic, however, few of them have read the book. (comma splice)
Correct:     Many people have seen the movie Titanic.  However, few of them have read the book.
Correct:     Many people have seen the movie Titanic; however, few of them have read the book.
Note that there is a comma following the adverb since it is actually a introductory word in this sentence.

9. Fixing a run-on
Conjunctions are words that join parts of a sentence. Coordinating and subordinating conjunctions can be used to fix run-ons.
Coordinating conjunctions are for, and, nor, but, or, yet, or so (FANBOYS).
Many people have seen the movie Titanic, but few of them have read the book.
Note that there must be a comma before a FANBOYS coordinating conjunction. 

10. Fixing a run-on
A subordinating conjunction can be used to join the sentences and fix a run-on. Here are some common subordinating conjunctions: if though since, although after, because before, while when. Use the memory helper ITS AA BB WW.
Many people have seen the movie Titanic although few of them have read the book.
Note that there is no comma before the word although. Unlike coordinating conjunctions, there is no rule to insert a comma before a subordinate clause when it follows the main clause. However, when it goes first, there must be a comma at the end since they are now introductory words.
Although few people have read the book, many people have seen the movie Titanic.

11. To Review
A run-on is a sentence which is missing proper end punctuation.
There could be two sentences with no punctuation.
There are called run-ons, fused run-ons, or fused sentence run-ons.
When there is a comma between two sentences, it is called a comma splice or a comma splice run on.
To fix a run-on, a period or other appropriate end punctuation may be used such as a question mark or exclamation point, as appropriate.

12. To Review
A semicolon may be used to separate two short, closely related sentences that seem to be one sentence.
If a conjunctive adverb (such as also, however, therefore, consequently) is used, there still must be a period or semicolon to separate the sentences.
Coordinating conjunctions (FANBOYS – for, and, nor, but, or, yet, so) may be used to fix run-ons. However, there must be a comma in front of them.

13. To Review
Subordinating conjunctions (if though since, although after, because before, while when ITS AA BB WW) may be used to fix a run-on.
If the subordinate clause is first, there must a comma after it since the clause would be introductory words. If the subordinate clause follows the main clause, there should not be a comma.