A semicolon (;) separates sentences that are closely related but grammatically independent. For example: “My brother isn’t feeling well
; he’s been sick for a week.” The two independent sentences could be separated by a period. A semicolon also works here since the two sentences are closely related.
You can also use semicolons to separate a list of items that contain commas. For instance: “I’ve been to Paris, France
; London, England; Rome, Italy; and Madrid, Spain.” Imagine how confusing reading that would be if there were commas where the semicolons are.