Why would you ever want to make your writing more complex by using a semicolon? The little comma-with-a-dot-over-it grammatical mark?
1. Semicolons are used when listing information in a sentence.
The best politicians can: 1) smile on command; 2) kiss babies by the truckload; and 3) spend other people’s money without remorse.
2. Semicolons are also used for effect.
A semicolon has the power to link two independent clauses so that they appear in a single sentence. You could just leave them as separate sentences, but by linking them with a semicolon you help your reader reflect on the connection between the ideas presented in the two clauses.
Barack Obama was the first African-American president; he was also the first 21st century president because he carries a Blackberry and doesn’t need three assistants to surf the internet for him.
This single sentence is quite long, but it draws attention to the contrast being made: that to many voters (and people around the world) it is Obama’s diversity of credentials, experience, and personal background that make him compelling. The single sentence would be just as correct with a period instead of a semicolon. But the semicolon helps get a longer sentence into the mix and makes a subtle point. For these reasons, semicolons should not be overused (maybe one or two per page, maximum).
Friends are like precious gems; treasure them and they will sparkle.
The beach’s pitch is steep; to find the most level walking I stay on high sand, away from the line of tides.