dnf
install software on Fedora and RHELdnf is the package manager of the Red Hat family. It does the job apt does on Debian: resolves dependencies and installs from signed repositories. The main difference in use is that there is no separate "update the list" step.
On Fedora and RHEL, dnf upgrade is the whole routine update.
At the terminal
Read the session first, then the notes: each numbered line in the output is answered by the note with the same number.
What the numbered lines are telling you
dnf checks how old its copy of the package lists is and updates them when needed.
Each package with its architecture, version, and the repository it comes from.
What will be installed, upgraded or removed, and how much will be downloaded.
The capital N is the default: pressing Enter cancels. -y answers yes in advance, for scripts.
Switches
A switch changes how the command behaves. These are the ones used day to day; man dnf lists the rest. Single-letter switches can usually be joined, so -l -a may be written -la.
-y- Answer yes to prompts.
--security- With upgrade, apply only security updates.
--refresh- Force the package lists to be downloaded again.
--assumeno- Answer no: show the transaction without doing it.
--enablerepo=NAME- Use a repository that is disabled by default, for this command.
-q- Quiet.
Variations worth knowing
The same tool, pointed at a narrower question. These four cover most of what it is reached for day to day.
sudo dnf upgradeUpdates every installed package.
dnf provides /usr/bin/digFinds which package supplies a file or command.
dnf historyLists past install and update transactions.
sudo dnf upgrade --securityInstalls only the updates marked as security fixes.
In cybersecurity
The package manager is the trusted path by which software reaches the machine.
gpgcheck=1 in the repository settings makes dnf refuse unsigned packages. Turning it off to "fix" an error removes the protection.
"dnf upgrade --security" applies fixes without other changes — useful on servers where every change must be justified.
"dnf history" records what was installed, when and by which user. Unexpected entries are worth following up.