The document discusses various methods for backing up and restoring the pfSense configuration file (config.xml) including:
1) Backing up config.xml from the GUI by downloading it as an XML file, which can optionally be encrypted.
2) Restoring config.xml from the GUI by uploading a backup file. Interface assignments may need to be adjusted during restore.
3) The configuration history in the GUI automatically backs up config.xml on changes and allows restoring previous versions.
4) Manually editing config.xml requires care to avoid breaking the XML format. Removing package information can prevent reinstalling unwanted packages.