This section introduces you to firmware manifests, the manifest tool and update campaigns. Firmware manifests encode information that devices use to make decisions about an update, such as whether to trust and accept an update, and when and how to apply it. The manifest tool is used to create, sign and upload these manifests. You can use update campaigns to define which devices receive a particular update and the firmware image that is installed. These campaigns are built around the firmware manifest that is sent to the device and a filter that determines which devices receive the manifest.