disown is a Bash builtin which allows you to run a job in the background and log off from your console. The job keeps running while the parent console is closed.
Syntax : disown job_id
To get the job_id, run the command jobs. You will see all the ids corresponding to the processes launched within your console.
nohup is an external command which does the same job.
Syntax : nohup your_command_line &
By default, nohup redirects stdout and stderr to a file named nohup.out.
Both can be used by non-root users.