The main purpose of the Corona Light Material is to illuminate the scene. The typical use case is light-emitting objects which have different shapes than the ones available in the Corona Light object (e.g. light bulbs, custom-shaped lights, curved LED strips).

Intensity – This option controls the intensity of the light. The intensity is the result of multiplying the color or the texture map and the intensity value.

Color – This is the color that is used for light emission.

Texture – This slot defines the texture map or shader that is used instead of the above color.

Mix mode – This parameter controls the blending mode of the texture map or shader over the color.

Mix strength – This value controls the intensity of the texture map or shader that is used.

Emit light – When the Light Emission is enabled, then this light is a proper emitter, casting illumination into the scene. It can be disabled to create a camera back-plate that does not alter the scene lighting.

Emit on both sides – When checked, the material also emits light on the reverse side of the normals from the objects that are using this material. When disabled, it only emits light using the normal front side.

Occlude other lights – When enabled, the light blocks shadow rays from other lights in the scene. It is geometry that casts shadows when other lights shine at it.

Shadowcatcher illuminator – Used in combination with the Shadow Catcher Material. If enabled, this light illuminates the shadow catcher instead of casting shadows on it. Enable for CG lights that are added to the footage and are not present in the 2D backplate/footage.

Directionality – This parameter controls how concentrated the light emission is around the normal. Higher values create a spotlight effect.

Include/Exclude – This parameter lets you include or exclude objects from the influence of the Corona Light Material (the excluded objects do not receive light from this Light Material). Available modes are: 

Include children – This allows affecting child objects when parent objects are defined in the include/exclude list.

Level – This is the intensity (also considered as the visibility) of the color.

Color – This is the color that is used for the opacity channel.

Texture – This slot defines the texture map or shader used instead of the above color.

Mix mode – This parameter controls the blending mode of the texture map or shader over the color.

Mix strength – This value controls the intensity of the texture map or shader that is used.

Visible directly – When enabled, this makes the Corona Light directly visible to the camera.

Visible in reflections – When enabled, this makes the Corona Light directly visible in reflections.

Visible in refractions – When enabled, this makes the Corona Light directly visible in refractions.

Visible to alpha channel – When enabled, then the light is displayed as opaque (white) in the alpha channel.

Visible in masks – When disabled, the material isn't visible in any masking pass (ID, mask, source color,etc.).

Generates caustics – Enabling this option allows for generating caustics.

Material ID – This parameter defines the ID used for this material.

In this example, the Corona Light Material is applied to the mesh behind the mirror, the ceiling spotlights, and the strip light in the top-right corner of the room.
They all have the Emit Light option enabled:

In this example, all Corona Light Materials have the Emit Light option disabled. They are only visible directly and in the reflections:

 In this example, the outdoor lighting comes from a Corona sky object placed in the scene. The lamps on the wall were imported from the Chaos Cosmos library and are only using a translucent lampshade material with no illumination. 

 Now, a Corona Light material is applied to the lamps on the wall, but the "Emit light" option is turned off (no light contribution at all). What seems to be a bit of lighting is actually just the reflection of the lamps on the wall.

In this example, a Corona Light material is applied to the lamps on the wall, and the "Emit light" option is enabled (you can clearly see the light contribution on the wall, but also on the ceiling, chairs, and other objects). The resulting image has a little bit of noise. 

Finally, a Corona Physical material using the Self-Illumination channel is assigned to the wall lamps (there is subtle light contribution), and the resulting noise level is higher compared to the other examples.

The Corona Light Material can be applied to Corona Decals. (Corona Physical Material with self-illumination can be used like this as well!)
In this example, Graffiti textures are being used as the emission texture of a Corona Light Material which is being projected by the Corona Decals.