1.The "erb" stands for "Embedded RuBy". .erb files look like about.html.erb and live in the "views" directory.They are just html files with embedded ruby in them.
2.The @ indicates that this is an "instance variable". An instance variable defined in the action (or function) of a controller is automatically available in the view of that same name.
3.puts (pronounced "put-ess")
4.It's a test that simulates a browser accessing our application.