The host groups page can be accessed via the The Configure Menu:
Configure > Host groups
As the name suggests, host groups allow you to group arbitrary hosts (see also All Hosts) in a structured way. The grouping is structured, since host groups support inheritance from parent host groups. Host groups are especially useful if you want to roll out a certain type of host multiple times. (For example, a fully configured database server).
Since host groups are intended for hosts that share a relevantly similar configuration, it is appropriate for the host groups page to be placed in the configure menu. However, host groups also bundle functionality relevant to orcharhino’s content management (Activation Keys in particular) and provisioning setup. (See also: Content Management Guide and Provisioning Setup).
By contrast, Host Collections provide host groupings, solely for the purposes of orcharhino’s content management.
Changing the provisioning parameters of an existing host group will only affect hosts provisioned via the host group at a later time (that is, it will not alter any existing hosts). However, configuration management changes for a host group will affect existing hosts.