There are precious few useful things that you can do in Inkscape without first selecting some object or objects. Of all Inkscape operations, selecting has, by far, the greatest number of methods, tools, dialogs, and shortcuts available. You need to know a good portion of them to be able to work efficiently, and at least a few of them to be able to work in Inkscape at all.
By itself, selecting or deselecting objects does not change the document in any way. Therefore, none of the techniques described in this chapter are undoable actions and none require the document to be saved.