Semicolons to Join Clauses
You should use a semicolon when you’re joining two independent clauses without a connecting word. The semicolon functions, structurally, just like a period. The difference is that the semicolon between the two independent clauses shows they are connected, as illustrated in the following examples:
I learned that one candidate started his career as a teacher; the other has only ever worked in corporate banking.
So semicolons replace a comma + connecting word (for, and, nor, but, or, yet, so). The following examples show what the sentences would look like if you used a comma and a connecting word:
I learned that one candidate started his career as a teacher, but the other has only ever worked in corporate banking.
Using semicolons tends to give both sentences a certain emphasis.