Heavy Metal became popular in the 1970's but its true roots lay buried in the late 1960's. The bands that created Heavy Metal took time to develop a molasses-thick sound, both sonically massive and characterised by distorted, fuzzy guitar riffs and elaborate solos. For once, the lead singer took somewhat of a back step to the guitarist, complimenting but not superseding the almighty riff; the back-bone of any Heavy Metal song. Brute force and a heavy, low-end sound, achieved by the bass rumbling in tandem with the central riff was introduced as standard and while the influence of the Blues and Psychedelia would linger, with each heavy riff, crushing beat and ear-piercing scream, changes were obviously on the horizon. Masculine, aggressive and positively bleeding machismo, the bands who forged Heavy Metal had only one agenda - to be loud enough to haemorrhage your ears and as the 70's wore on these fundamentals became the blueprint for a burgeoning new genre. Listed in chronological order, this article will detail the ground-breaking and revolutionary songs from the late 60s and early 70s which led to the inevitable birth of Heavy Metal. In other words, this is Heavy Metal 101. Pencils at the ready, we shall begin.....