1. The Semicolon (;) and the Colon (:)

2. Using a Semicolon
the punctuation mark ; that is used to separate major parts in a sentence and to separate items in a series if the items contain commas

3. To join two sentences…
The first appropriate use of the semicolon is to connect two related sentences. The pattern looks like this:
Complete sentence  + ; +  complete sentence .
Here is an example: My eighty-one-year-old grandmother still rides her Harley motorcycle; her toy poodle balances in a basket between the handlebars.

4. To join sentences if using a conjunctive adverb…
You can also team up a semicolon with a transition (Conjunctive adverb) to connect two complete sentences that are close in meaning. The pattern looks like this:  Complete sentence  + ; +  transition  + , +  complete sentence .
Check out this example: My father does not approve of his mother cruising around town on a Harley motorcycle; however, Grandma has never cared what anyone thinks.

5. To join items in a list that already has commas…
Finally, use the semicolon to avoid confusion when you have complicated lists of items. The pattern looks like this:  Item  + , +  More Information  + ; +  Item  + , +  More Information  + ; + and +  Item  + , +  More Information
Read the following example: On a Harley motorcycle, my grandmother and her poodle have traveled to Anchorage, Alaska; San Francisco, California; and Tijuana, Mexico.

6. Reminders about Semicolon Use
Keep these three things in mind when you use a semicolon:
 The two main clauses that the semicolon joins should be closely related in meaning.
 Don't capitalize the word that follows the semicolon unless that word is a proper noun, one that is always capitalized.
 Limit your use of semicolons; you should not scatter them wantonly throughout your writing. Semicolons are like glasses of champagne; save them for special occasions.

7. Use a Colon…
After a complete statement in order to introduce one or more directly related ideas, such as a series of directions, a list, or a quotation or other comment illustrating or explaining the statement. For example,

8. To offer an explanation…
The strategies of most high school English teachers have proven ineffective: compromises and concessions have left students unable to punctuate sentences correctly.

9. …to introduce a list…
The daily newspaper contains four sections: news, sports, entertainment, and classified ads.

10. between the hour and minutes.
He said he would be at home by 5:30 p.m.

11. between chapter and verse in biblical references.
He always liked to refer to Genesis 1:18 when starting a speech.

12. Caution
Space once between a colon and the next word, when the colon is used between words. Do not space between numerals and a colon when a colon is used to mark time or ratios.