How do ; work?

While the semicolon looks cute, it’s not actually winking; in fact, it has quite a serious job. It’s purpose? To indicate a strong connective pause between two clauses. Semicolons are neither as strong as a full stop nor like the pause of a comma, but somewhere in the middle.

Like many things, semicolons have rules. We use semicolons:

[1] to link two independent clauses with a related meaning:

• Some people write on a laptop; others with a pen.

[2] to separate items in a list, particularly when grammatically complex:

• You may use the hotel facilities for the duration of your stay with access granted through your keycard; some facilities have opening times and these are stated at the entrance; scan your card at the entrance to the Member’s Club; for purchases, scan your card at PurchasePoint scanners.

Examples

[A] I prefer dogs, however, I don’t like cleaning up after them. ❌
[B] I prefer dogs; however, I don’t like cleaning up after them. ✅

However signals a connection between two independent clauses so a comma [A] cannot be used.

[C] I like cows. Why? They give us milk, which is good for us, they give us beef, which is great for barbecues, and we have leather, which is excellent for shoes and coats. ❌
[D] I like cows. Why? They give us milk, which is good for us; they give us beef, which is great for barbecues; and we have leather, which is excellent for shoes and coats. ✅

Semicolons make it clear what is separated by a comma and what is in the list [D].

[E] Rather than cats, it is the dog who is considered man’s best friend, it is the canine who is loyal, not the proud  independent feline. ❌
[F] Rather than cats, it is the dog who is considered man’s best friend; it is the canine who is loyal, not the proud  independent feline. ✅

It’s unclear where the first independent clause ends and the second independent clause begins. The semicolon makes this clear in [F].