Batteries not included: The concept of »DevOps« beyond buzzwords

»DevOps« is everywhere and the buzzword machines seem to work overtime, resulting in a lot of misunderstandings and fancy new marketing shenanigans.
But whatʼs really behind the term »DevOps«? What impact does it have on working relationships and company culture, not only for developer and operation teams? And why does reality often lag far behind the demands when it comes to implementation?