Key difference: Semicolons are used to join two different parts in a single sentence. Colons are used to introduce something related to the sentence.

The subtleties of the English language can be quite confusing, to English speakers as well as non-English speakers. The difference between the usage of a semicolon and a colon is one of those subtleties. A semicolon is used to combine two independent clauses into one sentence. A colon, on the other hand, is used to introduce something new into the sentence that is directly related to the first part of the sentence.

A semicolon, which is represented by the symbol (;), is used to separate a sentence into two different parts. Another way to say this is that it shows the relationship between two independent clauses. An independent clause is basically a complete thought. For example, Mike received a raise; his salary nearly doubled.

Semicolons are used in the following situations:

• Before conjunctions (e.g. ...is true; but the other one...)
• Before transitional phrases (e.g. ...he knew; as a result, I was...)
• In lists (e.g. the master, aged 71; the servant, aged 21)
• To extend a sentence (e.g. It was serious; I broke a leg.)

A colon, represented by the symbol (:), is mainly used to introduce something, or list some detail. For example, I can remember the following flowers from the top of my head: roses, violets, and carnations.

Colons are used in the following situations:

• To extend a sentence (e.g. ...one trait: bravery.)
• In references (e.g. Para. 4: Section 2)
• For introductions (e.g. ...the following: A and B.)
• With bullet points (see above)
• Before quotations (e.g. Lisa said: “…)
• To separate subtitles from titles (e.g. Colons and Semicolons: When to use them)

For further clarification, consider this example:

Ben was upset. Mary was hurt.

The use of the period shows that they are two different sentences. There is no connection between them. They just happen to be true at the same time.

Now see what happens when a semicolon is used:

Ben was upset; Mary was hurt.

The semicolon now suggests that the two statements are related. It suggests that the reason for Ben’s emotion and Mary’s hurt was the same, perhaps there were involved in an accident.

Now let’s try a colon:

Ben was upset: Mary was hurt.

This suggests that the sentences are directly related. It states that Ben was upset because Mary was hurt. 

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