1. fg is a bash builtin command:

   $ type fg fg is a shell builtin

To get information on individual bash commands, use `help`:

    $ help fg
    fg: fg [job_spec]
        Move job to the foreground.
        
        Place the job identified by JOB_SPEC in the foreground, making it the
        current job.  If JOB_SPEC is not present, the shell's notion of the
        current job is used.
        
        Exit Status:
        Status of command placed in foreground, or failure if an error occurs.

2. 1>&2 is an example of redirection. To read about redirection, run man bash and go to the section entitled REDIRECTION.

1. fg is a bash builtin command:

   $ type fg fg is a shell builtin

To get information on individual bash commands, use `help`:

    $ help fg
    fg: fg [job_spec]
        Move job to the foreground.
        
        Place the job identified by JOB_SPEC in the foreground, making it the
        current job.  If JOB_SPEC is not present, the shell's notion of the
        current job is used.
        
        Exit Status:
        Status of command placed in foreground, or failure if an error occurs.

2. As mentioned in the first version of the question, 1>&2 is an example of redirection. To read about redirection, run man bash and go to the section entitled REDIRECTION.