“Smart quotes,” the correct quotation marks and apostrophes, are curly or sloped. “Dumb quotes,” or straight quotes, are a vestigial constraint from typewriters when using one key for two different marks helped save space on a keyboard. Unfortunately, many improper marks make their way onto websites because of dumb defaults in applications and CMSs. Luckily, using correct quotation marks and apostrophes today is easier than you think.
A cheat sheet for using the right quotation marks in your writing: