Correctly combining independent clauses (making compound or compound-complex sentences and avoiding run-ons and comma-spliced sentences)

One way to join two independent clauses together in the same sentence is to use the coordinating conjunctions or FANBOYS

For	Connects an effect to a cause (works like because)	I stayed home, for I was sick.
And	Shows a simple connection, adds two sentences together	I came home, and my mother made me do chores.
Nor	Connects two options which will not be taken	I will not go home, nor will I stay here.
But	Shows contrast between two sentences	I may come to school, but I will not stay awake.
Or	Connects two options	I will do my homework, or I will fail.
Yet	Shows contrast, but the contrast is unexpected	I am not getting married, yet my mother insists on buying my wedding dress
So	Connects a cause to an effect	I was sick, so I stayed home.

For is seldom used in American English as a conjunction except in very formal writings. Usually the second sentence is changed into a dependent clause using because. I stayed home because I was sick.

Nor and Or are also seldom used, and when they are, most people use them correctly.

Yet is frequently misused as a substitute for but. Yet should only be used for an unexpected contrast.

So can be tricky in a sentence. If the two clauses being connected are cause and effect, use so with a comma to join the clauses.

Example: I was sick, so I stayed home.

If so is used to connect something to a reason for that thing and if the word that can be placed after the word so, then do not place a comma before so. In this case, the second clause is a dependent clause.

Example: I stayed home so (that) I could watch television.

And and But are the most common conjunctions used. If they are used to connect two words or phrases, however, a comma should not come before the conjunction.

Example: I like ice cream and cake.

Example: I like asparagus but hate brussel sprouts.

 

Using semicolons to connect independent clauses

A semicolon by itself can be used to connect two independent clauses. However, this is rarely done. As a rule, two conditions are necessary in order to use a semicolon as the only thing connecting two independent clauses:

• The main ideas of the two sentences must have a very close connection to each other, and
• At least one of the two sentences must be short.

The coordinating conjunctions not only connect independent clauses, but they indicate something about the relationship between the ideas contained in each independent clause (c.f., but shows contrast). This is lost when the only thing connecting the two independent clauses is a semicolon. It is possible, however, to show the relationship between independent clauses when using a semicolon to connect the clauses. Writers often include conjunctive adverbs with the semicolon. These conjunctive adverbs (see page 100 in Writing with Confidence) show relationships the same way coordinating conjunctions do. The pattern for using conjunctive adverbs with semicolons to join independent clauses is

Independent clause; conjunctive adverb, independent clause.

Note that the semicolon comes where a period would go at the end of the first independent clause and that a comma follows the conjunctive adverb.

Semicolons with conjunctive adverbs are the "good china" of language. Students should use these when writing formal papers and not when writing personal paragraphs or essays. Words like thus, nevertheless, and hence are too formal for "everyday use."