Most (if not all) writers have problems with using punctuation effectively, especially commas. But, arguably, the most misunderstood piece of punctuation is the semicolon (;).
The semicolon can be used in two different ways: to connect two ideas and to separate items in a list. The second usage, while not quite as common, is easier to understand, so let’s start there.
Here’s a simple list:
While packing for the trip, we made sure to bring beach chairs, two kites, and a beach ball.
In order to use semicolons to separate items, the items need to have more to them. Semicolons separate items in a list when commas are used within items so as to avoid confusion. Let’s beef up our list a bit:
While packing for the trip, we made sure to bring beach chairs, one for each person; a dragon kite and a bumblebee kite; and an extra-large beach ball.
Here’s another example with semicolons in a list from the most recent issue of Science:
Four groups of interest are highlighted: G1, ancestral sequences that have almost been completely lost from the human lineage; G2, ancestral sequences that are largely fixed but rarely deleted (also absent in human reference); G3, ancestral sequences that have become copy-number variable since the divergence of humans and Neanderthals/Denisovans ~700 ka; and G4, sequences potentially lost in Neanderthals and Denisovans since their divergence from humans.
Now for the harder stuff. I’m calling on The Writing Center at The University of Wisconsin – Madison for this part as they have a wonderful Grammar and Punctuation Section on their website. We’ll start with this sample sentence from their semicolon section:
Some people write with a word processor; others write with a pen or pencil.
Two independent clauses are linked with the semicolon. While this could be rewritten as two separate sentences, the main point of using semicolons to link ideas is to show a close relationship between the two clauses; plus, there are multiple ways to set this relationship up (See what I did there?). I’ll rewrite Wisconsin’s sample sentence to show you how my tutees usually set up semicolons using conjunctive adverbs:
Some people write with a word processor; however, there are still people who choose to write with a pen or pencil.
I’ll also adjust the first two sentences of our sample Science text to show you how this pattern might look in a STEM piece.
In the past decade, genome sequencing has provided insights into demography and migration patterns of human populations, ancient DNA, de novo mutation rates, and the relative deleteriousness and frequency of coding mutations; however, global human diversity has only been partially sampled and the genetic architecture of many populations remains uncharacterized.
In the WRC, I usually see semicolons (when used correctly) paired with “however.” This may be because “however” on its own establishes a relationship between the original idea and the one that is about to be contrasted to the original, making it a bit easier to understand why and how a semicolon works in that situation.
Of course, if you find that you’re not comfortable with or confident about using semicolons, then don’t! While I may be the #1 Fan of the semicolon, it doesn’t mean that everyone has to like and use them (even though they’re super fabulous…). If you do want to use semicolons in your writing, I suggest you start out with using no more than one per paragraph (if that). Once you’ve become comfortable with using them, run free!
Happy Writing, Everyone!
The University of Wisconsin – Madison Writing Center’s Grammar and Punctuation Section
The University of Wisconsin – Madison Writing Center’s “Using Semicolons”
The Oatmeal “How to Use a Semicolon”