An art model poses, often nude, for visual artists as part of the creative process, providing a reference for the human body in a work of art. As an occupation, modeling requires the often strenuous 'physical work' of holding poses for the required length of time, the 'aesthetic work' of performing a variety of interesting poses, and the 'emotional work' of maintaining a socially ambiguous role. While the role of nude models is well-established as a necessary part of artistic practice, public nudity remains transgressive, and models may be vulnerable to stigmatization or exploitation. Artists may also have family and friends pose for them, in particular for works with costumed figures.