The semicolon is the one of the most hotly contested punctuation marks in the English language. There are those who would fight and die for the semicolon, and there are others who would rather see it subjected to firing squad. However, the greatest majority simply just doesn’t think much about semicolons at all. The popularity of the punctuation has decreased significantly since its heyday around two centuries ago. Some may abstain from semicolon simply out of spite for a punctuation mark that seems—at least on the surface—totally redundant. Others simply aren’t sure how to use it and would rather save themselves the embarrassment of any possible grammatical slipups; I mean, regular colons are hard enough as it is. So to clear the water, the commonly accepted uses according to the Writing Center at the University of Wisconsin are the following:
Link two independent clauses to connect closely related ideas: Some people write with a word processor; others write with a pen or pencil.
Link clauses connected by conjunctive adverbs or transitional phrases to connect closely related ideas: But however they choose to write, people are allowed to make their own decisions; as a result, many people swear by their writing methods.
Link lists where the items contain commas to avoid confusion between list items: There are basically two ways to write: with a pen or pencil, which is inexpensive and easily accessible; or by computer and printer, which is more expensive but quick and neat. Link lengthy clauses or clauses with commas to avoid confusion between clauses: Some people write with a word processor, typewriter, or a computer; but others, for different reasons, choose to write with a pen or pencil. The semicolon, at a very basic level, is the equivalent of a full stop period or a comma followed by a conjunction. It is not, however, identical in its effect. Imagine three couples in various seating situations. Two austere business personalities sit adjacent to one another at a bar, maybe even a stool between the two of them. They might share a drink; they’re there for the same reason after all. But they most certainly don’t touch. Periods. Now imagine two youths snuggled into a loveseat, watching Love Actually, limbs practically indistinguishable from each other. These are commas, united under one clause, one cause, and minimal pause. A world of difference lies between the two. If only there were some levelheaded punctuation to bridge this gap. But wait! On the other side of the room, you see a couple sitting across from one another. The man wears a grey suit, worn with use and age. The woman’s maroon skirt runs longer than it may have in her youth. She considered wearing a scarf tonight; her neckline is awfully lowcut, but what the hell? It’s Friday. The couple talks of nothing but their children. They’ve gotten a babysitter for the night. She laughs, he grins, and their hands drift slowly toward the equator of the table. Without ever breaking eye contact, the two hands find each other blindly, by memory. They exchange a brief squeeze, warm, familiar, and separate—but not quite; this is a semicolon.
McMullen, Ruth. Divorce the Semicolon? https://ruthmcmullen.wordpress.com/tag/historyofsemicolon/
Dolnick, Ben. “Semicolons: A Love Story” http://opinionator.blogs.nytimes.com/2012/07/02/semicolonsalovestory/?_r=0