"Hipster" has a nebulous definition, maybe intentionally so. A quick skim through the index of the n+1 book, What Was the Hipster?, which highlights words and phrases such as Bike: fixed gear, Midwestern sensibilities, ironic, gentrification, twee, and cafe, can help to piece together a semi-lucid image.
The book also mentions Richard Florida's The Rise of the Creative Class, a 10-year-old sociological study that predicted a flocking of talented, creative types to more urban areas, leading to a culture that greatly values diversity and sustainability. Sound familiar?