The O-1 visa is a temporary employment visa available for aliens of extraordinary ability in the arts, sciences, athletics, education or business. In practice, this includes nearly any field of endeavor: puppeteers, figure skaters, scientific researchers, and more. The O visa can be a welcome option for highly talented individuals who are not eligible for another type of visa. O visas are granted for the duration of an "event" (i.e. a grant, project, tour, etc.) and for an initial period of no longer than three years. Extensions for the O visa are easy and unlimited, usually granted in increments of 1 year at a time.