Uptalk - or what linguists often call HRT (High Rising Terminals) or HRI (High Rising Intonation) - is a feature in which the usual falling cadence at the end of a statement is replaced with a rising intonation, so that - to some listeners, at least - the tone sounds more like a question. Like y'know, one time at band camp?
In previous research, the phenomenon was shown to be spreading out of the USA and Australia where it might have originated (although views are mixed on exactly where) and into the language of younger British people, mostly young females. But work done by Amalia Arvanati, from the University of Kent suggests that uptalk is spreading into male speech too, although its use may be under-reported by males because it's felt to be a female feature or perhaps because it carries connotations of insecurity.
Uptalk is a useful feature of language, because it can signal a desire for the interlocutor (conversational partner) to confirm something that a speaker has said, but it can also grate on some listeners, because of this perceived lack of self-belief and certainty. As Arvanati explains on the programme, "It grates on people - some people think it sounds really ditzy or insecure".
We looked at uptalk back here in 2010 and you can find a lot more about it in this article from 2001 by Matt Seaton and in this piece by the linguist Mark Liberman on Language Log (which suggests, incidentally, that HRT is not a good term to describe uptalk). If you want to track uptalk back to its origins then this piece in the New York Times by James Gorman is credited (by Liberman, at least) as being the first recorded reference to it (from 1993).