Comma vs Semicolon vs Colon

Many people are confused by punctuation marks, especially with the differences between the comma, semi colon, and colon. Although each punctuation mark has numerous rules associated with its use, it’s not hard to get to grips with the basics.


Commas are one of the most used and misused punctuation marks of the English language. Many people have misconceptions about the use of commas, while others have given up completely and simply place them where it is convenient.

By knowing the rules of grammar, the writer has more options available for sentence construction

Commas are used inside of a sentence to create a mental pause for the reader as well as to separate grammatical constructions, which also can use that mental pause but not a full stop. A comma can identify extra information in the sentence, with the comma placed before and after the extra information. For example, “Hal sat on a park bench, wobbly and squeaky, to eat his lunch.” The description of the park bench is not necessary for the sentence to be complete: it just adds extra and interesting detail.

A comma can also break up two complete sentences that are joined by a coordinating conjunction (for, and, nor, but, or, yet, so). For example, “Millie wandered the store for hours, yet she bought nothing.” The “, yet” separates two complete sentences; a period could have been used for the same grammatical correctness but not for the same reading experience.

In addition, commas often separate the main clause (with the most important idea) from subordinating clauses (a.k.a. dependent clauses) that offer information of secondary importance. For example with a verbal phrase, “Jack sat on a wobbly stool, eating his cold oatmeal.” For another example, “Although Josh had a great modeling career, he threw it all way by behaving badly at shoots.” Note that the main clauses carry the most important information.


Semi colons separate two complete sentences that are closely related in thought. In other words, the second sentence (the one after the semi colon) relates directly to the first sentence, usually continuing the first idea with more detail. For example, “Jessica stared at the body; she cringed inside.” Of course, the semi colon could be replaced with a period, but that change often creates choppy writing in which the sentences all sound the same.

The semi colon could also be replaced by other connecting constructions such as creating a verbal phrase (for example, “…, cringing inside.”) or using a coordinating conjunction (for example, “…, and she cringed inside.”).

The tricky use of semi colons comes when using transitional elements such as however, moreover, consequently, and many others. If you remember that a semi colon usually divides two complete sentences (they have other uses, to be discussed in other articles), then you will know when to use a semi colon as opposed to a comma, which is used for a single sentence. For example, “Zeta consulted with her mentor; however, she left dissatisfied with the advice.” This example contains two complete sentences divided by the semi colon and however. For the example with a single sentence, use this: “Zeta consulted with her mentor, however leaving dissatisfied with the advice.” The second sentence in the first example has been changed to a verbal phrase, thus making the entire example one sentence.


Colons are used to introduce a list or further explanation at the end of a sentence. For example, “Joey played with his toys: a red fire truck, a black and white police car, and a white and red ambulance.” The sentence could also read, “Joey played with his toys: public service vehicles with lights and sirens.”

Colons can also be used to separate two complete sentences with the second sentence explaining the first. For example, “She was proud of her son: he won first prize.” Note that both sentences are complete, but the second adds more detail and explanation to the first.

As with semi colons and commas, the colons can be replaced by other grammatical constructions because the English language is flexible, offering many options for any sentence to be written. That is one reason for writers staring out the window while writing: they are often trying out various ways of expressing an idea. With one chosen, the writer looks back at the page or screen and writes in her choice.

A Comparison of Three

Comma vs Semicolon vs Colon

While all three punctuation marks appear in the interior of a sentence, a comma retains the completeness of the sentence, while a semi colon does not. Both a semi colon and colon can divide two complete sentences. A comma and a colon can divide a complete sentence into pieces while retaining its wholeness.

Writers need to learn the rules of grammar for their own advantage. First, knowing the rules will enable them to communicate their ideas properly. Second, by knowing the rules of grammar, the writer has more options available for sentence construction, thus making the writing experience more interesting for the writer and the reading better for the reader.

I hope this article has helped to clarify the use of these three punctuation marks.

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