sXe is an offshoot of punk culture that focusses on control. Straight-edge is about controlling your life. This means no alcohol, narcotics, smoking, or promiscuous sex. Many straight-edgers also become vegetarians or vegans but that's not a requirement for being straight-edge. Additionally, many straight-edgers don't use caffeine. Poison-free.

Straight-edge originated with the Minor Threat song Straight Edge. The X's come from "all-ages" punk shows where minors had X's put on their hands to show they couldn't buy alcohol. Straight-edgers started putting X's on their hands as a show of solidarity.

It seems I'm a straight-edge, though I'd never heard of it before yesterday.