What it is is a "package" that depends on a prefdefined set of installable items.
It is for ease of installation.
Instead of and apt-get install <insert 350 specific packages to get a "workable" install of KDE>
You get to do this:apt-get install kde
-- [link|mailto:greg@gregfolkert.net|greg], [link|http://www.iwethey.org/ed_curry|REMEMBER ED CURRY!] @ iwethey Freedom is not FREE. Yeah, but 10s of Trillions of US Dollars?