Network admin

It has its own menu: Sites, Users, Themes, Plugins, Settings, and Updates. A plugin is network activated here, a theme is enabled for the network, and a new site is added from Sites > Add New. The user needs the manage_network capability, which only Super Admin accounts carry.

You can confirm the list of super admins with wp super-admin list, or by reading the site_admins option stored in wp_sitemeta.

A publisher with 60 magazine sites on a network wants a caching plugin everywhere. A Super Admin opens Network Admin > Plugins and clicks Network Activate. Sixty sites are now running it, but the plugin's settings page appears under each site, so each editor must set their own options.

Later a freelancer asks to install a theme. Site admins cannot do it because Network Settings has theme installation off, and only the Super Admin can add it under Network Admin > Themes.

The network admin governs the whole network, while each site's wp-admin governs one site. Anything installed in Network Admin is available across sites, but only a site admin can change that site's content, menus, and local settings. Site admins also cannot see other sites' users unless they are added.

Network-activating a plugin that was written for single sites. Giving Super Admin to a client to avoid support requests. Changing Network Settings, such as allowed upload types, and forgetting it affects every site. Running updates on a live network without testing on one site. Looking for plugin settings in the network menu when they live in each site.

Keep the Super Admin list to the fewest people possible. Before network-activating, enable a plugin on two sites and check for conflicts. Review Network Settings > Upload and Registration settings once a year.