You may hear these devices referred to as either "silencers" or "suppressors." In fact, the inventor of the technology, Hiram P. Maxim, named it the "Maxim Silencer." It's not hard to imagine why he did so: His father, Sir Hiram Stevens Maxim, was the inventor of the modern machine gun. The elder Maxim went profoundly deaf by the end of his life, no doubt in part due to damage caused by prolonged exposure to gunfire. However, the truth is that what comes out of a "silencer" isn't exactly "silent," just quieter than an unsuppressed gunshot would be, so they're also commonly termed "suppressors."
Whatever you call them, what they really are is a way to make shooting safer and more enjoyable for everyone, especially beginners. In this video from American Hunter, we walk you through why you should have and use suppressors for your firearms.