You don’t have to turn your smartphone off at the Providence Performing Arts Center — at least not if you’re sitting in the “tweet seats.”

The theater is now setting aside a small number of seats for those who promise to live-tweet the performance. Twitter users might offer impressions of the set, music or costumes, or lines from the show that resonate with them.

At a recent staging of the musical “Million Dollar Baby,” even a few cast members were tweeting from backstage.

A growing number of theaters, including some on Broadway, have been experimenting in recent years with tweet seats and other real-time uses of social media. Some insist theaters should remain free of smartphones, but others say theaters can’t afford not to engage the digital generation.