What am I?

Many have heard me, but nobody has seen me, and I will not speak back until spoken to. What am I?

related riddles

You use a knife to slice my head but you weep beside me when I am dead. What am I?

I can be entertaining until you realize some pieces have been lost. What am I?

Everybody has some. You can lose some, you can gain some. But you cannot live without it. What am I?