If you use Fedora, you know that, for many important software, you need to install RPM Fusion software repositories to be able installing app in a easy way.
So, to install both Free and Nonfree repositories of RPM Fusion on Fedora 26 Alpha and later, you must use the following command in a terminal window:
sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm
RPM Fusion provides software that the Fedora Project or Red Hat doesn’t want to ship. That software is provided as precompiled RPMs for all current Fedora versions and current Red Hat Enterprise Linux or clones versions; you can use the RPM Fusion repositories with tools like yum and PackageKit;
FREE REPO is for Open Source Software (as defined by the Fedora Licensing Guidelines) which the Fedora project cannot ship due to other reasons;
NONFREE REPO is for redistributable software that is not Open Source Software (as defined by the Fedora Licensing Guidelines); this includes software with publicly available source-code that has “no commercial use”-like restrictions.