What are “conjunctive adverbs”?

The purpose of conjunctive adverbs is to join clauses, phrases, or ideas. When joining two independent clauses, conjunctive adverbs are performing the same function as coordinating conjunctions; however, the rules of punctuation are different (Simmons 2013).

Here is a list of common conjunctive adverbs:

The Rules

The rules of punctuation when using conjunctive adverbs vary depending on the placement and use of the adverb. See punctuating conjuctive adverbs

There are three main variations:

If the adverb separates two independent clauses, the structure is as follows:
Clause1; adverb, clause2. Notice how the clauses are separated with a semicolon instead of a comma.
If the adverb falls anywhere within a single independent clause, the adverb and clause are separated by a comma:
Adverb, clause. or Beginning of clause, adverb, end of clause. or Clause, adverb ("Using Conjunctive Adverbs" 2012).
If the adverb creates a weak interruption within a sentence, no commas are necessary (Simmons 2013).

Here are some examples of each variation that correspond with the bullets in the above section:

    Ex. Alice accepted Robert's invitation to the prom; subsequently, she spent the rest of her day thinking about what to wear.

    Ex. Conversely, Robert could focus on nothing with so many thoughts running through his mind.

    Ex. When the prom came, everything was perfect. Robert and Alice could finally enjoy their time together.

How to punctuate conjunctive adverbs:

When a conjunctive adverb connects two independent clauses in one sentence, it is followed by a semicolon and then usually a comma.

Example:

Alice read her book; therefore, she was able to go to the party.

As you can see, semi-colon is put after book, and because therefore is the adverb, we follow it with a comma.

Due to budget cuts, critics on rotten tomatoes may lose their jobs; consequently, their finances may fall apart.

If a conjunctive adverb is used in any other position in a sentence, it is set off by commas.

Example:

Meanwhile, Alice continues to read Science Fiction while soaking her feet in the bath.

Bruce Springstien, however, maintains a huge smile as he walks through the vacant house.

The adverbs used here are meanwhile and however: when used properly, they are almost always followed by a comma.

Simmons, Robin L. "The Conjunctive Adverb." The Conjunctive Adverb. N.p., 2013. Web. 14 Nov. 2013. <http://www.chompchomp.com/terms/conjunctiveadverb.htm>.
"Using Conjunctive Adverbs." Grammar and Punctuation:. Board of Regents of the University of Wisconsin System, 2 July 2012. Web. 14 Nov. 2013. <http://writing.wisc.edu/Handbook/ConjAdv.html>.