For disambiguation, you may consult the Periodic Table of the Elements, or hold a magnet up to your computer screen. Advanced users might want to repeatedly rub a powerful magnet against their motherboard.
For the purposes of this article, "METAL" refers, without much internal distinction, to (A) a bunch of elements in the southwest quadrant of the aforementioned Periodic Table; (B) as Figure 1 demonstrates, astronomers consider to be metal any element with enough protons that its nucleus constitutes an act of group sex; C) any kind of music, musician, or music fan who conducts electricity well enough to maximize the amplitude of one's hair.
Gallium, an element with the atomic number of 31, has such a low melting point that it will actually melt in one's hand. When protected by a candy-shell, however, it often survives the trip to the mouth without liquefying.
In "The Empire Strikes Back," the whole rebel base thingy on the planet of Hoth is made of gallium, whereas on Tattoine, it is much prized as a beverage, and is used as a solvent to clean between the folds of Jabba's fat.
Metal lyrics are unique for being anti-Romantic, anti-Modern, and anti-unique. They often concern themselves with a deep critique of the predominant impulses of modern society, and a recognition that those impulses also exist within the critic. For example, see the first track on Metallica's "Master of Puppets," in which James Hetfield bemoans that he "cannot kill the battery/ cannot kill the family," and goes on to concede that the "battery is found in me."
(Presumably, Hetfield is referring to a 12-Volt car battery; many scholars of the genre doubt that the energy storage device in question can be purchased at Radio Shack.)