To copy data from memory to storage. While some apps continually save changes, most applications prompt the user to save data upon exiting. However, if a drawing or image is being created or edited, the user decides when it should be saved.
Save to Storage
All processing is done in memory (RAM). When the processing is completed, the data must be placed onto a permanent storage medium, which is either a hard drive or solid state drive (SSD). Decades ago, storage was magnetic tape. See
Save As.