You can put a task (such as command or script) in a background by appending a & at the end of the command line. The & operator puts command in the background and free up your terminal. The command which runs in background is called a job. You can type other command while background command is running. The syntax is:
/path/to/command arg1 arg2 &
Example:
$ ls *.py > output.txt &
Source: http://www.cyberciti.biz/faq/linux-command-line-run-in-background/