an "it girl" is an attractive young woman, who is perceived to have both sex appeal and a personality that is especially engaging
the expression "it girl" originated in British upper-class society around the turn of the 20th century. It gained further attention in 1927 with the popularity of the Paramount Studios film "It", starring Clara Bow. In the earlier usage, a woman was especially perceived as an "it girl" if she had achieved a high level of popularity without flaunting her sexuality. Today, the term is used more to apply simply to fame and beauty. The Oxford English Dictionary distinguishes between the chiefly American usage of "a glamorous, vivacious, or sexually attractive actress, model, etc.", and the chiefly British usage of "a young, rich woman who has achieved celebrity because of her socialite lifestyle". The terms "it boy" or "it man" are sometimes used to describe a male exhibiting similar traits
since the 1980s, the term "it girl" has been used slightly differently, referring to a wealthy, normally unemployed, young woman who is pictured in tabloids going to many parties often in the company of other celebrities, receiving media coverage in spite of no real personal achievements or TV hosting / presenting. The writer William Donaldson observed that, having initially been coined in the 1920s, the term was applied in the 1990s to describe "a young woman of noticeable 'sex appeal' who occupied herself by shoe shopping and party-going"
the prominence of an "it girl" is often temporary; some of the rising "it girls" will either become fully-fledged celebrities, commonly initially via appearances on reality TV shows or series; lacking such an accelerant, their popularity will normally fade
