In the long-running BBC television science fiction programme Doctor Who and related works, the term companion refers to a character who travels with, or shares the adventures of the Doctor. In most Doctor Who stories, the primary companion acts as an audience surrogate. He or she provides the lens through which the viewer is introduced to the series. The companion character, many times, furthers the story by asking questions and getting into trouble, or by helping, rescuing or challenging the Doctor. This designation is applied to a character by the shows producers, and appears in the BBCs promotional material and off-screen fictional terminology. Until the modern revival of the series in 2005, the term was rarely used on-screen. The Doctor also refers to the shows other leads as his friends or assistants; the British press have also used the latter term.