The curation's outcome requires a durability story stated as a procedure rather than a feeling, and this node supplies the mechanism the two recovery numbers are derived from: what exists to restore from, how far back it goes, and what the act of restoring actually produces. It presupposes the log retention already introduced with the storage volume, and it is the direct parent of the objectives node, whose figures are meaningless to a learner who does not know that a restore stands up a new server.
Video tutorial: Three Common Strategies for Backing Up SQL Server Databases