What sources of revenue does a government have/ How important are taxes?

What percentage of the government's money comes from Taxes? What other sources of revenue does the government have? Would it be possible to fund a government without taxes?

I need this information for a debate I'm having at school, so any answers are welcome (but if you could provide sources I'd be very happy :P)

taxes are what funds the government, that is the cost of having it. without them, where else do they get the money? the only other choice would be to voluntarily ask the people to contribute, and that's not likely to happen. they could never get enough to even cover basic expenses like roads, police and firemen

here is a link with arguments for volentary taxation

http://www.geocities.com/CapitolHill/5357/cc36vtax.html

tax-

A compulsory contribution, usually of money, that is required for the support of a government: assessment, duty, impost, levy, tariff. See money, pay/owe, politics.