A placeholder name is a word which is used to refer to a person or object. Placeholder names are used in a variety of situations, and each region of the world has its own unique, distinctive, and sometimes quite colorful placeholder names. Some examples of placeholder names for people include: John Q. Public, Jane Doe, Average Joe, Joe Citizen, and Richard Roe. Objects may be referred to as things, thingies, widgets, gizmos, gadgets, thingamabobs, whatsits, and so forth.
Often, a placeholder name is used when someone does not know what something is called, as might happen when someone asks someone else to “pass the widget.” Terms like “thingie” are also used when the official name of something is unwieldy or hard to remember, or when an object has not quite been invented or named yet. For example, someone might say that he or she is “working on a gizmo which will do x.” Many professional communities have placeholder names for objects which take the form of inside jokes.
For people, placeholder names are often used to describe a mythological average person. “John Q. Public,” for instance, pops up in a great number of political speeches, with candidates using his fictional wants and needs to bolster their campaigns. Many companies encourage their developers to create products which will appeal to average people, saying that “this product should be easy enough for Joe Citizen to use right out of the box.” The placeholder name used to describe a theoretical person tends to be plain and unremarkable, with a very ordinary and average nature.
Printers and designers use placeholder names in their work so that something occupies the space dedicated to a name, allowing people to say how the finished piece will look; designers also often use nonsense text for the same purpose. People will also, of course, use a placeholder name when they cannot remember or don't know what someone is called, saying things like “there goes whatshisname” or “that waitress, whatshername, can be quite frosty.” Placeholder names are also used in the legal field to protect anonymity or to discuss people who have not been identified, such as murder victims.
In computing, placeholder names are used for a variety of purposes. Software manuals often use a placeholder name for files to demonstrate how a piece of software should be used, with directions to indicate that the name of the file should be changed by the user. Companies may also use placeholder names to refer to software internally before a final name for the product is developed; naming is actually a highly profitable industry, with numerous well known consulting firms which specialize in creating ideal product names.