A preface to the description: In the United States libertarianism—as opposed to concerns about liberty, which are also found on the left—is typically associated with the political right. In other places around the globe there are people on the left who identify as libertarians, or its equivalent in other languages, who espouse anarchism and/or socialism. There is actually something called libertarian socialism, which can be viewed as a form of anarchism.* The picture is further complicated by the fact that there are many shades of anarchism, and there are even libertarian socialists/anarchists in the United States. But this is not our concern, since we are describing main-stream libertarianism in the U.S.
So, here is right-wing libertarianism in the U.S. described in a 100 or so words:
Libertarianism: a philosophical or political doctrine that tells us that certain kinds of liberty—usually tied to the freedom to manufacture, buy, and sell commodities, as well as the freedom to own (lots) of property—are to be protected at all costs, even at the price of losing a sense of fellowship with other human beings. This doctrine is most actively and effectively supported by rich white guys or guys aspiring to be rich white guys, who typically believe that self-gratification is a sacred activity. Many of its leading advocates cluster in a place called Silicon Valley and confuse technological or strategic rationality with reason.
*See, anti-libertarian Noam Chomsky’s brief description of different types of libertarianism: