This is a quick way to re-select Illustrator paths of a certain type such as a selection of green colored paths or paths with a stroke etc or any custom selection. Create a path and set the color etc. Create another path and set the color etc. Select some text etc. Select some of the paths. Go to the select menu and select the save selection command. That is it. OK, now you have your stored entry. You can repeat this any time you wish with different groups of objects
You can then quickly access / restore via the select menu via the 'selection 1' 'selection 2' etc (or whatever you name them). This is a super quick way of grouping paths quickly again. You should note that is doesn't matter if you alter the artwork, it is the path id that matters so if you change the type or change the color etc then it can still be restored into that group of objects.
All of the groupings are stored when you save your work. On re-opening, you will see them all again in the menu, If you create a new document, that menu has been cleared down.
If you delete some paths, and you ad added them to one of the entries, it doesn't matter. Only those that still exist will again be used. The others are ignored and for once, the application doesn't pop up a dialog telling you it can't find the paths.
There is an edit selection and this sadly does not allow for the addition or removal of paths from but it does just offer the option to remove the preset from the menu list (which is, I suppose, useful if you build up a lot of pointless entries)
You can also use the feature to store points alone in the grouping, not the entire path. Use the direct selection tool on some points and then use the menu command and give it a name and you will see that added to the menu. To restore only those, just select it from the menu presets and you will see only those point active.