Fr. Mike comments on whether swearing, as in using vulgar language, is a sin. He gives three times when using vulgar words can be sinful:
Remember that we are called to always be charitable. Our words mean something. We are called to build people up, not bring them down. The words we choose reflect and express what’s in our hearts “for out of the abundance of the heart his mouth speaks” (Luke 6:45). What do you want to express, words that are at best crude or words that build people up?