If you want to write English more effectively, then you should use the colon and semicolon. They look and sound similar, but they have very different uses. This website explains how to use them both, and how to know which one is suitable for the task in hand.
Simply put, the colon is used to provide a pause before introducing related information, while the semicolon is just a break in a sentence that is stronger than a comma but not as final as a full stop.
A quick guide to using the colon
One common use of the colon is to introduce a list of items. For example:
To make the perfect jam sandwich you need three things: some bread, butter and strawberry jam.
Three items are listed in the sentence above. The first part of the sentence informs the reader that there will be three things; then the colon tells the reader “here are the three items”.
A colon can also be used to introduce a definition, statement or explanation of something. For example:
I know how I’m going to handle this: I’m going to hide!
Penguin (noun): an aquatic, flightless bird found almost exclusively in the Antarctic.
A quick guide to using the semicolon
The most common use of the semicolon is to join together two clauses that could each be separate sentences — creating a longer sentence. For example:
John calls it football; Sam calls it soccer.
This could be written as two sentences without the semicolon; however, the relationship between the two clauses is made more clear through the use of a semicolon. The semicolon is often used to make the reader think about the relationship between the two clauses.
The semicolon is also commonly used to join two clauses, changing the sentence in combination with words like ‘therefore’, ‘however’ or ‘on the other hand’. The examples below illustrate this approach:
Sian is Welsh; however, she lives in Canada.
He likes to play video games; in addition, he likes to read classical literature.
You should stop drinking too much alcohol; otherwise, you’re going to get into trouble.
Hundreds of people came to the party; therefore, it was not possible to say hello to everyone individually.