levio_sah

Most of you guys are incoherent, so I'll try my best:straight-edge is a philosphy that originated from the hardcore punk movement in Washington D.C. The term was coined by Ian MacKaye in his song 'Straight Edge' by Minor Threat, but he did not intend for his personal stance to become a movement.
Straight edge esouses the refrainment from recreational drugs, cigarettes, alchohol, and casual sex (although the casual sex part seems to have gotten less popular). Later on, some believers of the straight edge philosophy added qualities such as veganism, vegetarianism, abstinence, and refrainment from caffine, but these things were not part of the orgininal straight edge philosophy.
In the 1990's, a new faction of straight edge called "hardline" came into existance. Followers of the 'hardline' moevement aften used violence against non straight edge people, were firmly vegan and anti-abortion, and have been acused of being evangelical, homophobic, and even neo-fascist by some. There is a long running conflict between hardline and 'normal' straight edge.
One does not neccesarily need to listen to hardcore punk to live by the straight edge philosohpy, but the straight edge hardcore fans generally appreciate that you at least has a knowledge of it's roots.

Hope this helps!

levio_sah

Edit: I realized that straight edge could be called a lifestyle instead of a philosophy. Please consider the terms interchangable.