Command explaination?
 

I am working off of a guide:
http://www.howtoforge.com/opennms_network_management

I am installing Postgressql and my instruction say to

Initialize database

$bin/initdb -D data/

What is the $ before the command mean?

"$" is the prompt of the bash shell for regular user.
But if you login as root user then the prompt will be like "#".

Thank you!!!