comma versus semicolon

The other use for semicolons involves lists of items (also called a series). Normally, items in the series are separated by commas.  

Three people came West on the wagon: Charles Imus, John Imus, and John Laird.

Charles Imus, John Imus, and John Laird were the first settlers on the West Side plain.

However, when one or more items in the series requires an internal comma, the commas separating the items are replaced by semicolons.

Three people came West on the wagon: Charles Imus; John Imus, who was Charles' son; and John Laird.

Charles Imus; John Imus, who was Charles' son; and John Laird were the first settlers on the West Side plain.

This sort of structure can become difficult to read, and many writers try to avoid its overuse.

Nested commas, such as may occur with a parenthetical phrase, can also confuse the reader. ("Such as may occur ..." is a parenthetical phrase.)  When that occurs in my writing, I prefer to set the parenthetical phrase apart either by enclosing it with parenthesis marks or em-dashes.

The wagon's occupants became the first settlers on the West Side plain.

The wagon's occupants, Charles Imus, John Imus, and John Laird, were the first settlers on the West Side plain. (acceptable but difficult to follow)

The wagon's occupants, Charles Imus, John Imus, who was Charles' son, and John Laird, were the first settlers on the West Side plain. (even worse and not acceptable)

The wagon's occupants (Charles Imus; John Imus, who was Charles' son; and John Laird) were the first settlers on the West Side plain. (with parenthesis and semicolons)

The wagon's occupants--Charles Imus; John Imus, who was Charle's son; and John Laird--were the first settlers on the West Side plain. (with em-dashes)

Semicolons are used less comman than commas because they are a last resort, and not always the best solution. I hope this helps.

Some people write with a word processor; others write with a pen or pencil.

Okay, we've talked in the past about compound sentences -- two independent clauses joined by a comma + conjunction.

Some people write with a word processor, and others write with a pencil.

Some people write with a word processor, but I write with a pen.

You may also join two independent clauses with a semicolon. The semicolon represents more of a pause than does the comma, but less than a period. When you use a semicolon, you omit the conjunction.

Some people write with a word processor; others write with a pencil.

Some people write with a word processor; I write with a pen.

You only use the semicolon when the two independent clauses are closely related. Because a period will also serve, most teachers/editors prefer the period to the semicolon except in rare, special cases where the link between the two thoughts needs emphasis.

Some people write with a word processor. Others write with a pencil.

Some people write with a word processor. I write on paper.

There is another use for the semicolon, but I will save that for another time.