Inkscape has a number of dialogs for manipulating various properties of objects, but only one of them is so generic as to be called simply Object Properties (accessible by pressing 
or by choosing a command in the Object menu). This dialog is quite small, as shown in Figure 4-1.
You need to select (Chapter 5) a single object to view its properties in this dialog. The identifier (ID) of an object is the id attribute of the corresponding element in the SVG source of the document (Appendix A). Its value is always unique inside this document; Inkscape provides unique IDs for all objects automatically. You can, however, change this value as long as it remains unique.
Assigning meaningful names to objects is a useful approach to organizing complex artwork. However, the ID is not the best place to do this, because according to XML rules, you can only use a very limited set of characters in element IDs: no spaces, only Latin letters, digits, hyphens, underscores, and dots. For a more human-friendly alternative, set the object’s label in the Label field (which corresponds to the inkscape:label extension attribute in SVG). Here, you can compose an arbitrary label or description for your object; it can be any length, use any character, and need not be unique.
SVG
The Title and Description fields can contain additional freeform metadata about the object (they are the standard title and desc elements of SVG). Since these values are stored in elements, not attributes, they can even contain child elements such as text markup (though you cannot do this via the Object Properties dialog).
The Interactivity part of the dialog (folded up by default; click the triangular mark to unfold it) allows you to edit values of the interactivity attributes (such as onclick, onmouseover, and so on) which are used in SVG with Javascript. Inkscape does not support Javascript, but this can be useful if you want to view your SVG in a Javascript-enabled viewer.
At the bottom of the dialog, two checkboxes control the locked and hidden status of the selected object. A locked object is visible, but most selection methods cannot select it, so it is therefore impossible to change. A hidden object is both invisible and unselectable.
I would not recommend hiding or locking individual objects. It is usually much more convenient to act on the layer containing the objects you want to hide or lock. Hiding and locking via layers is better not only because it affects multiple objects at a time, but also because a layer, even if locked or hidden, can always be easily accessed (via the Layers dialog, see 4.6.4 The Layers Dialog) and its status changed.
With objects, however, many users find themselves in a trap: You need to select the object to unlock or unhide it, but you cannot easily select it because it is hidden or locked. Specifically for such situations, the Object menu contains two commands, Unhide All and Unlock All, that will reveal and make selectable all objects in the current layer.