Final answer:
A colon is used to introduce lists, summaries, and quotations, while a semicolon is used to join main clauses and separate items in a series. Commas should not be used to join independent clauses.
Step-by-step explanation:
Colons
A colon is used to introduce lists, summaries, and quotations, as well as to separate titles from subtitles. For example, in the sentence 'Julie went to the store for some groceries: milk, bread, coffee, and cheese,' the colon is used to announce a list of items that describes the noun 'groceries' in more detail.
Semicolons
A semicolon is used to join main clauses that are connected by a transitional word or phrase, like 'for example' or 'however.' It can also be used to separate items in a series that already contain commas. For example, in the sentence 'I finally found my keys; I got to work just in time,' the semicolon is used to connect two main clauses. In the sentence 'It rained heavily during the afternoon; however, we still managed to have a picnic,' the semicolon is used to separate two clauses within a sentence.
Commas
Commas are not used to connect independent clauses. Instead, a period, semicolon, or coordinating conjunction should be used. For example, 'I finally found my keys, and I got to work just in time.' Avoid using commas to join independent clauses, as in 'I finally found my keys, I got to work just in time,' which is a comma splice.