Parent and Child questions

Hi Everyone,

I have recently been studying WordPress in hopes of improving my ability to manage my own website better. I’m not understanding a few things about how Parent Themes vs Child Themes tha hopefully someone here can clarify for me.

1 I understand the purpose of having a child theme but when viewed by the internet public which are they seeing? The Child or the Parent?

2. In order to setup a Parent , child, theme setup you have to copy and move some files around. Right now I’m practicing on a localhost on my own network. How does this work if and when I migrate my site to an outside hosting? Do I still have the ability to change my WP files from their site?

Thanks for any clarity you can give me on this.

Dale