How to use a colon is a grammar rule that both native and non-native speakers have trouble with. There are a 2 main reasons to use a colon.
The most common use is with a list.
I love so many kinds of fruits: bananas, strawberries, blueberries and raspberries.
Did you notice that the first part (clause) of the sentence could also be a sentence by itself? “I love so many kinds of fruits.” is a sentence. To use a colon, you must first have a clause thatworks as a sentence by itself, and then you can separate it from a list with a colon. I’ll include 2 more examples.
Jen has three ideas: open a grocery store, open a shoe store or open a video game store.
Sam likes three beaches the best: Pacific Beach, Caswell Beach and North Beach.
You can also use a colon for a ratio.
If I brew tea and I use 8 cups of water and 1 cup of sugar, there is an 8:1 ratio of water to sugar.
Study this page so you can use a colon confidently!