Writing well is a lot more than just correct grammar, but it is an important element.

Do you know the difference between colons ( : ) and semi-colons ( ; )? Here are the rules.

Use colons:

• between the hour and minutes-8:15
• after the salutation of a business letter-Dear Madam:
• to introduce a list, examples, a series of statements, or a long quotation. The only trick here is that the part of the sentence that comes before the colon must be a complete sentence. Correct-Jim took three courses last semester: Old Testament, Hebrew, and HCE. Incorrect: My favorite foods are: spinach, okra, and turnips.

Use semi-colons:

• between two clauses of a compound sentence when they are not connected by a conjunction. Correct: It's going to snow this weekend; I need to get out the shovels. Incorrect-It's going to snow this weekend; and I need to get out the shovels.
• between independent clauses which are joined by a conjunctive adverb such as therefore, hence, however, nevertheless, accordingly, then, and thus. Correct-I partied too hardy last night; consequently, I failed my Greek test.

Don't rely on the grammar checker on your computer. It often does not catch these. These are but a few of the rules for colons and semicolons. Check a grammar handbook for more details.