there is also sasparilla (or sometimes sarsparilla) and sassafrass teas, and also a carbonated beverage that is a bit smoother called birch beer, which uses the oils extracted from birch bark and roots, delicious. so root beer, is

a) not beer (any longer, though some home brewers do make an alcoholic version)

b) made from roots of certain trees and shrubs, like some tonics in medicinal concoctions, and still having some residual medicnal or tonic application

c) today a sweet, syrupy carbonated beverage, delicious with a scoop of vanilla ice cream, called a 'root beer float' (or in some areas a 'Boston Cooler', though there is wide disagreement and much hard feelings about the misuse of this term!)