From the Commas, Semicolons, and Colons video; the video will start automatically in browsers where autoplay of audio is enabled. If the video doesn't immediately begin, click the pause button and then click play.
Sentences are comprised of independent and dependent clauses. Independent clauses contain a subject and a verb, and as their name suggests, they can stand alone without additional information e.g., the sun is shining. Dependent clauses also contain a subject and a verb, but they are incomplete sentences that need an independent clause to make sense e.g., which is a pleasant surprise. Together, independent and dependent clauses create full sentences e.g., The sun is shining, which is a pleasant surprise.
Colons are used in sentences:
American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.). https://doi.org/10.1037/0000165-000
Harnett, C. (2016, January 28). Crofton-area road closed by washout; Trans-Canada traffic flowing. Times Colonist. http://www.timescolonist.com/news/local/crofton-area-road-closed-by-washout-trans-canada-traffic-flowing-1.2160792