Blueprints are used for VMware vCenter virtual server management. It allows from the ESXi Compute resources at vCenter, and creating blueprints from that images within the OnApp Control Panel.
Using blueprint templates, OnApp administrators can create and manage multiple virtual servers as a single multi-tiered application (blueprint). A single blueprint template is a pre-configured template that contains virtual server operating system and the configuration settings (network configuration and firewall rules). Utilization of blueprints allows you to create sets of different types of servers: for example, web servers, database, etc. based on imported vApps templates.
Blueprint management is described in the Blueprints section of the vCenter Implementation guide.