What is and how to execute commands starting with $?

Question

Command line

Yes, I'm dumb and a humanist, but it would be nice to have a couple of articles about this for presentation. I do not know how to formulate a query in Google.
Examples:
(tilde) $ git clone https://github.com/username/username.github.io
$ curl https://install.meteor.com/ | sh

Answer 1

The dollar sign or percent sign means that the command is being executed as a simple user.
The pound sign means that the command is being executed on behalf of the super user, i.e. root.
These characters at the beginning of the command do not need to be entered!