Brand and toggle get grouped for better mobile display Toggle navigation Collect the nav links, forms, and other content for toggling Pages Categories Tags Archive /.navbar-collapse fastest cheapest reliable An Operating System (O/S) is a set of libraries that abstract your hardware and which mean that your unwritten software can speak to persistent storay, networks, input/output devices, etc, etc. Similarly a Cluster System (C/S) is a set of libraries that run across many computers (with different O/Ses) which means that your unwritten software can scale horizontally, failover when a computer goes down, have hardware replaced under it ...comprende? Yes, the best known one is the Google App Engine. But, like in the early days of operating systems, most running C/S are in-house and custom-built in big companies like Facebook, Twitter etc. Amazon provid...