A handheld microphone is a medium-sized mic designed to be held by the performer or clipped to a stand. They're mainly used for work like speeches and live vocals over a PA system, but examples like Shure's SM58 is sometimes seen on screen as a general purpose interview mic or used as a general purpose post-production tool for voice-overs. Handheld mics are normally very robust, dynamic mics, so they'll withstand loads of abuse and require no independent power source for them to work.