4.1. Service Offerings, Disk Offerings, Network Offerings, and Templates

A user creating a new instance can make a variety of choices about its characteristics and capabilities. CloudStack provides several ways to present users with choices when creating a new instance:

Service Offerings, defined by the CloudStack administrator, provide a choice of CPU speed, number of CPUs, RAM size, tags on the root disk, and other choices. See Creating a New Compute Offering.
Disk Offerings, defined by the CloudStack administrator, provide a choice of disk size for primary data storage. See Creating a New Disk Offering.
Network Offerings, defined by the CloudStack administrator, describe the feature set that is available to end users from the virtual router or external networking devices on a given guest network. See Network Offerings.
Templates, defined by the CloudStack administrator or by any CloudStack user, are the base OS images that the user can choose from when creating a new instance. For example, CloudStack includes CentOS as a template. See Working with Templates.

In addition to these choices that are provided for users, there is another type of service offering which is available only to the CloudStack root administrator, and is used for configuring virtual infrastructure resources. For more information, see Upgrading a Virtual Router with System Service Offerings.