openSUSE, as its name implies, is an open distro and the base of the SUSE Linux Enterprise commercial one. SUSE was the top European distro and the alternative to Red Hat, at least until the arrival of Ubuntu. SUSE adopted Red Hat’s idea of having a community version of its commercial distro, and openSUSE received a good reception from the community, so good that it eventually displaced SUSE as the chosen distro for regular users. The SUSE family of distros have always been very well maintained, designed, and finished products. openSUSE was for years one of the few distros that was sold in a box, accompanied by a large printed manual; you can still purchase openSUSE in this manner in Germany (only in the German language, however).