It is used to describe people between the ages of early twenties and late thirties, generally of the middle-to-upper class[?]. Yuppies tend to be fresh from graduate school[?] and hold a job in the professional sector, and follow all the latest trends. In many cases, in the late 1990s, yuppies looked and sounded a lot like the cast of Friends.
Most people use the term dismissively.
Perhaps the classic image of the Yuppie (in the United Kingdom at least) is that of the '80s Yuppie complete with red suspenders/braces[?], mobile phone the size of a brick, filofax[?], and optional pony-tail[?].
There exists a similar term: Yumpie: a "Young Upwardly-Mobile Person". While this term is far less common, many confuse the derivation for Yuppie with that of Yumpie, and the two express broadly the same connotations anyway.
Compare Hippie.
wikipedia.org dumped 2003-03-17 with terodump