While you can light a model railroad layout using room lights, most larger layouts have lighting as part of the layout design, either specialized room lighting or additional lights to directly illuminate the tracks and scenery. A number of considerations go into the design of this lighting, and as with most things, there are trade-offs to be made.
This section is a general one about lights used to illuminate a model railroad layout for viewers. For information on the specific lighting of my layout, see the Lighting the Layout section. For information about lighting models on the layout, see any of several pages in the Electricity for Modelers section.