Landscape Preset Camera Mode

Landscape mode is generally designated by a icon representing a mountain. This setting's primary function is to allow a large depth of field. To accomplish this the camera defaults to a small aperture setting in this mode. While this creates a large depth of field, it also has an alternate effect of creating a need for more light to properly expose an image. This means that the camera may use a slow enough shutter speed to create the need for a tripod.

Still, this preset is very useful for well-lit landscapes when a tripod is not available. Also, this setting is well-used for portraits when you want the background to be in focus.

Source : http://photography.about.com