Colons follow independent clauses (clauses that could stand alone as sentences) and can be used to present an explanation, draw attention to something, or join ideas together.

An example of a descriptive sentence using a colon:

There was only one terrible option for the vile monster: get horrid revenge on his heartless creator.

An example of a colon being used to introduce a list:

Victor quickly grabbed the items he needed: a long, twisty rope to climb high places; a small, but deadly pocket knife incase the vile monster threatened to attack; a tiny bottle containing vicious poison to pour into what the horrid creature would eat.

These sentences are based off the story Frankenstein by Mary Shelley