what does the $ as a variable do?

people are reporting a bug in steam. apparently there is a line in it that
is deleting all the personal data all connected read/write media.
this is how the line reads:


rm -rf $STEAMROOT/*


what does the '$' expand too?
:-)~MIKE~(-:
---------------------------------------------------
PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org
To subscribe, unsubscribe, or to change your mail settings:
http://lists.phxlinux.org/mailman/listinfo/plug-discuss