Usage Note: It is sometimes claimed that one should not use however to begin a sentence, but few writers consistently follow this rule. In our 2015 survey, only 10 percent of the Usage Panel reported that they themselves always follow the rule, 30 percent said that they usually or sometimes follow it, and 60 percent said that they rarely or never do so. And consistent with their self-reports, two thirds of the Panel judged a sentence beginning with however to be completely acceptable, and another quarter of them judged it at least somewhat acceptable—in other words, fewer than ten percent of them objected to it. · When however is used to join clauses within a sentence, it acts as a conjunctive adverb like nevertheless, not as a coordinating conjunction like but or yet. The conventions of punctuation thus require that it be preceded by a semicolon, as in Main Street will be closed to traffic for the parade; however, the stores along it will remain open. Using a comma instead of a semicolon is likely to be perceived as a mistake. In our 2015 survey, 86 percent of the Usage Panel gave an unacceptable rating to the sentence Main Street will be closed to traffic for the parade, however, the stores along it will remain open. See Usage Notes at but, whatever.