A colon is that punctuation mark which is used for three grammatical purposes. Those three purposes are:
1. To introduce a list
2. To explain the first clause
3. To use before a quotation
Let us explain these uses of a colon one by one.
1. To Introduce a list
You can use a colon to introduce a list. For example,
• I think you have three things in your pocket: a pen, a small diary, and a mobile phone.
• Please bring five things from market: vegetables, fruits, yogurt, milk, bread, and eggs.
You see in the above examples that colons are used after the independent clauses. For instance, in the first example, ‘… a pen, a small diary, and a mobile phone’ is a dependent clause. You should be careful in using a colon. Always place a colon after the independent clause. This is the rule!
2. To Explain the First Clause
One of the three grammatical uses of a colon is that it is used in between the two main clauses. In this way, the second clause explains the first clause. By using this, a writer can explain his thought intensely. For example,
• I know I am done with my work: just to live an exciting life.
• Hundreds days in Switzerland: unforgettable time of my life.
3. To Use Before a Quotation
A colon is also used before a quotation or a direct speech. For example,
• She said: “Arrive early if you really want a big slice of the chocolate cake.”
• The boss ordered: “I want all the files ready just after two hours.”
Apart from the grammatical uses of a colon, there are also a few non-grammatical uses of a colon. For instance, in ratios, titles, time, references, etc. Let me briefly explain few of them.
1. The colon is used in writing time, for instance, to separate minutes from hours.
• 9:30 p.m.
• 2:35 a.m.
• 11:00 a.m.
2. The colon is used in stating references like biblical references. The colon is used to separate chapters from verses.
• Genesis 1:27
• Genesis 1:26
3. The colons are used in stating the ratios as well.
4. You can find out colons used in formal letters as well.
• Respected Ma’am Madonna:
• To whom it may concern:
Note: Don’t use semicolon after a salutation.
5. Separation of titles and subtitles can be done by using a colon.
• Aphorism: The Girl that is a Beauty
• Intraseasonal Variability: Processes, Predictability and Prospects for Prediction
Remember a Few Rules
Only capitalize the first word after a colon when the first word is a proper noun or there is an independent clause. For example,
• I have only two best friends: Amelia and Leo.
• Forget everything: Be happy!
Sometimes, writers do use a colon before a list and just after a preposition or a verb or the words like including. This is not grammatically correct. You should avoid using a colon in this case. For example,
• The dress that I want should be: pretty, cool, and cheap. (Incorrect)
• There are many good things in this shop such as: laptops, video games, mobile phones, digital cameras, etc. (Incorrect)
In the first example, there is no need to place a colon. The sentence will be grammatically correct without any punctuation mark. The same case is with the second example.
A colon is a punctuation mark that has mainly three grammatical uses and a few non-grammatical uses as well. It is used after an independent clause to introduce a list, to explain, or to use before a quotation.