Free Grammar Help—Punctuation— Semi-colons
A semicolon is used to designate a pause in a sentence; it is stronger than a comma, but weaker than a period. At one time these punctuation marks were known as "semi-periods." The two parts of the sentence separated by the semicolon must be closely related.
There are three principle uses for a semicolon:
1. To separate items in a list where the items are lengthy or include commas;
2. To fix a run-on sentence by converting it to a sentence with parallel structure;
3. To separate main clauses joined by a conjunctive adverb.
(Conjunctive adverbs include the words: however, nevertheless, moreover, therefore, consequently, hence, indeed, likewise, furthermore, namely, still and then.)
EXAMPLE: We went to the mountains to go skiing; however, the rain washed the snow away.
Note that when the conjunctive adverb comes within the second main clause instead of at the beginning, the clauses still must be separated by a semicolon, and the conjunctive adverb set off by commas.
EXAMPLE: Canadians spend millions of dollars for road-building; our roads, however, are still full of pot holes.
Conjunctive adverbs are different from subordinating conjunctions. A conjunctive adverb is primarily a transitional word carrying the thought from one main clause to the next. Subordinating conjunctions introduce subordinate clauses. Subordinating conjunctions include: when, although, though, since, if, because, so that, as, after in order that, while and unless. These do not take a semicolon.