A lavalier (or lapel) microphone is small. It’s designed to be clipped to your clothing. They were invented for the TV camera
Generally the pickup pattern is omnidirectional, in order to pick up sounds from the speaker whose mouth is located near—but not directly in front of—the microphone.
Set it up and forget it. This helps put the interviewee at ease; there’s no big imposing microphone that constantly reminds the person, “Yikes, this is being recorded.”
If you’re videotaping the interview, this microphone photographs well.
The speaker has so completely forgotten the mic that she or he accidentally brushes against it. Also, its presence may interfere with that mode of speaking.