This is an advanced topic.
How the save function works.
The save (file or folder) contains any changes that you want to keep. Settings, configurations, added software, etc......
It is loaded when Puppy Linux boots, so that all these changes are available to use, and you do not need to do them all over again.
The save is actually a Linux file system inside a file or folder. The save is loaded (layered into the operating file system) when Puppy Linux boots. It does not load into RAM, but all the parts of the file system in the save become layered into the operating file system. To the operating file system, it all looks and operates as one complete file system.
When something in the save is accessed and used, it is read and put into ram.
The save is read/writable at all times. Write control depends on which pupmode Puppy Linux OS is using. The pupmode is determined by detecting a save to use, device Puppy is installed on, and command options that can be in the boot menu entries.
These are the ones used the most:
pupmode 5 -> uses a save ramdisk (a temporary set aside section of RAM) as the save. Auto writes are made to it at any time something needs to be in the save. This mode runs the very first time you boot Puppy Linux and have not made a save file/folder to use. On first shutdown if you choose to make a save, the stuff in the save ramdisk is written to the save file or folder.
pupmode 12 -> during boot if a save is found to use, writes are done to it as needed. Do something that needs to be put in the save and it gets written to the save, at the same time. This is used when installed on a hard drive or a drive where writing often is no big issue.
pupmode 13 ->writes are made at a set time, when you click on the desktop save icon, or at shutdown. Usually used on devices to limit the number of writes. (USB flash drives, etc....). This pupmode also uses a save ramdisk, that is automatically written to, any time something needs to be in the save. Stuff in the save ramdisk only gets written to the actual save, when auto save, save icon, or shutdown process does it.
You can adjust the auto save frequency by using settings in Puppy Event Manager -> Save Session
Auto save can be set to any time period to do an auto save or set to 0 and do no auto save.
Ask to save at shutdown can be set, so you get asked to update the save (only saves if you select save). If not selected to ask, save will be auto updated at shutdown.