There is a certain amount of debate about how the word "hippie" came about, and who coined the term. But hey, who owns a word anyway?
While working as a journalist in San Francisco, I was consistently told that long-time San Francisco Chronicle columnist Herb Caen had first penned the title in the mid-60s for a group of long-haired, happy-go-lucky teens and twentysomethings who had begun to hang out the Victorian houses in the Haight-Ashbury neighborhood. Allegedly, the word was a deviation from "hipster," a term which has seen a new life lately, but was originally was assigned to the Beat Generation cool kids, poets, and wanderers—a group that had its roots in New York City's Greenwich Village, but also a strong foothold in the Italian neighborhood of North Beach in San Francisco.
There certainly is some familiarity between the Beats and the hippies, like a little brother who is a bit more lighthearted and carefree, but the same DNA of tossing off the constraints about whatever is mainstream, and adopting new forms of music and dress (until, of course, Banana Republic, a San Francisco-based company itself, co-opts the look).
The irony about hippies is that their counter-culture attitudes glom together in a similar mindset, one that often is as uniform as the "squares" and normals they are rejecting. Yet, over the decades, hippies have changed and evolved, adopting new music tastes (from the Dead to Phish to bluegrass), emphasizing one element of the original hippies (dirtiness for the wookies, leaving a small footprint for the metrohippies) over another, and branching off into sub-genres and classifications. It can be hard to keep track, as they spring up new cultures faster than bacteria in a petri dish. Here's a starter course: