From BlenderWiki

Lights

As previously said, there are multiple types of lighting in Blender, like indirect light or ambient light. However, one of the more used are “lights”, or “lamps”. In this section, we will talk of general info and settings for these lights (you will find more lamp-specific details in the Lamps part):

• Light Properties – settings common to all lamps.
• Light Attenuation.
• Textures – how to apply texture(s) to lamps.
• What Light Affects.
• Lights In Other Contexts – lamp-related setting in other contexts.