This month marks the 20th anniversary of Garbage’s self-titled debut, the album responsible for such ’90s megahits as “Only Happy When It Rains” and “Stupid Girl.” It’s an important record for many reasons, not the least of which is that it helped bridge the gap between noisy alternative rock and mainstream pop — incorporating everything from burgeoning electronica to buzz-saw guitars and just the slightest whiffs of trip-hoppy industrial music. If you were of college-age back in 1995, Garbage was the kind of record that everyone seemed to have some sort of relationship with — from somber gay goth boys like myself blasting “Vow” at peak volume while smoking clove cigarettes in their dorm rooms to legions of newly converted Shirley Manson acolytes aggressively dyeing their hair red and stomping around campus in combat boots and mini-dresses. Garbage was a pop record, to be sure, but it was just genre-bending and weird enough that almost anyone could access it. And unless you didn’t have access to radio and MTV, there was no way to avoid it. The LP spent more than a year haunting the US and UK charts, and eventually sold more than 4 million copies worldwide. Looking back, it’s hard to imagine another ’90s band capable of making a top 20 single called “Queer” seem like the most natural thing in the world. It’s equally impossible to imagine the ’90s without Shirley Manson, who was exactly the kind of angry pop heroine the decade so desperately needed.