Answer:
I cost no money to use, or conscious effort to take part of. And as far as you can see, there is nothing to me. But without me, you are dead.
Though I have neither legs nor feet, my use is for to go; Although I cannot speak, I tell what others want to know
Look into my face and I'm everybody. Scratch my back and I'm nobody.
What is it that was given to you, belongs only to you. And yet your friends use it more than you do?
In many years, not much has happened. In many minutes, a lot has happened. In one second, everything has happened.
My days are numbered. What am I?