Use of Colon

Use of Colon

1. To Introduce a List:

We use a colon before a list of things if there is an independent clause/a complete sentence before that list. The list will not begin as a new sentence, so do not capitalize the first letter for that.

There are 8 parts of speech in English: noun, pronoun, verb, adverb, adjective, preposition, conjunction, and interjection. 
I have visited three countries: Bangladesh, Japan, and India. [B was capital because a country's name is a proper noun]


Incorrect: I am good at: chess, table tennis, and squash. ["I am good at" is a dependent clause/incomplete sentence, so we cannot use the colon]

Correct: I am good at chess, table tennis, and English grammar.
Correct: I am good at three things: chess, table tennis, and English grammar.

2. Writing a Ratio

The ratio of applicants to available positions was almost 50 to 1
The ratio of applicants to available positions was almost 50:1