One of the things that can make AutoCAD a tough nut to crack is the somewhat cavalier naming conventions used in the program's documentation. For years, things like lines, arcs, and other graphical items were called entities, but more recently, they started being called objects. Fair enough, but object has also long been used to define certain non-graphical components of a drawing — things that you'd hardly consider to be objects at all — and those are the kind of “named objects” I describe in what follows.
Hidden in the innards of every AutoCAD drawing file is a set of named objects. Named objects are organized into symbol tables, and the properties that are common to all AutoCAD objects are defined in these tables. For example, all the line objects in a drawing are stored on one or more layers, so a layer property is common to all lines and is defined in the layer table. But the coordinates that define the start and end points of a given line are unique to that line (or they should be!) — so the coordinate properties are not common to all lines.
Layers are one example of a named object. The layer table in a given drawing contains a list of the layers in the current drawing, along with the settings for each layer (color, linetype, on/off setting, and so on).
Named objects don't appear as graphical objects in your drawing. They're like the hard-working pit ...