A conjunctive adverb is a word like however or therefore. Others include nonetheless, consequently, even so, and others. We can use these words to join independent clauses. When you use them, however, make sure that you precede the word with a semicolon and follow it with a comma. Many people make the mistake of using a comma before the conjunctive adverb. Study these examples:
Wrong He passed the test, however he flunked the course.
Right He passed the test; however, he flunked the course.