A Red Hat Network channel is a collection of packages. Channels help to segregate packages by sensible rules: a channel may contain packages from a specific Red Hat distribution, for instance. A channel may contain packages for an application or family of applications. Users may also define channels for their own particular needs; a company may create a channel that contains packages for all of the organization's laptops, for example.
There are two types of channels: base channels and child channels. A base channel consists of packages based on a specific architecture and Red Hat Enterprise Linux release. A child channel is a channel associated with a base channel that contains extra packages.
A system must be subscribed to one base channel and one base channel only. A system can be subscribed to multiple child channels of its base channel. Only packages included in a system's subscribed channels can be installed or updated on that system through Red Hat Network.
When a system is registered with Red Hat Network, it is assigned to the base channel that corresponds to system's version of Red Hat Enterprise Linux. Once a system is registered, its default base channel may be changed to a private base channel; these changes can be made on a per-system basis in the RHN website.
On the Red Hat Network website, the Channels page (located under the Channels tab in the top navigation bar) provides a list of all base channels and their child channels. Clicking on the name of a channel displays the Channel Details page, which provides a list of all of the packages in that channel, its Errata, and any associated systems.
Remember, two different types of ISOs are available through the RHN website. Distribution ISOs represent distributions of the Red Hat Enterprise Linux operating system and contain only the packages. Channel Content ISOs, visible only to Satellite customers, also contain metadata in the form of XML that enable the Satellite to properly parse and serve the packages. Distribution ISOs can be found in the Easy ISOs page and the Downloads tab of the respective Channel Details page. Channel Content ISOs exist only on the Downloads tab of the Satellite's Channel Details page.