Stage Lighting is integral to the visual presentation of any artist, be they a Band performing a concert, an Actor in a Musical or Stageplay, or, A Magician performing in a Las Vegas Spectacular.
The Stage Lighting Designer uses his or her knowledge and experience of the craft to ensure that precisely the correct mood and atmosphere is conveyed to an audience in line with the action on stage. In the world of Stage Magic, this can be critical to avoid having the audience see (or not see) the mechanics of an Illusion or Trick.
Following consultation with the Artist and Show Director, Set and Costume Designer, the Lighting Designer will go away and draw up a plan that details the quantity, type and locations of equipment in the theatre relevant to the set and so on.
Using a wide variety of Lighting Fixtures and Colour Media, this equipment is then focussed and programmed (using increasingly sophisticated control systems) in time for rehersals with the Artist(s).
On a Long Running Show, the operation of the control system is generally handed over to the venues Chief Electrician, who replays each lighting cue as directed by the Deputy Stage Manager, who would have the cue points noted within their copy of the script.