Light List

The light list is available in the 3D view sidebar.

It displays a list of all the lamp objects and mesh lights (objects with emissive materials) in your scene, as well as settings for the World environment.

Here is a list of all the buttons and options:

General

Button	Function
Refresh Light List	Generally the light list should update automatically, but if you find that a light is not present in the list, you can manually refresh it with this button. Automatic refreshing can be disabled in the preferences if you always want to refresh it manually.
Visible Lights Only	Only show lights that are not hidden.
Visible Collections Only	Only show lights that are in a collection that is not hidden.
Show all Advanced	Expand the panels of all lights to show extra settings for each one.
Global Exposure	Chance the overall brightness of your scene with one slider.
Apply Exposure	Brighten/darken all lights in your scene according to the Global Exposure value and set it back to zero.

Per-light

Button	Context	Function
Show Advanced		Expand this light to show some extra less common settings
Lamp name		The name of the lamp
Users	lights that have data with multiple users	The number of other objects that share the same data/material as this light. Clicking the button copies the common object name to the data name (i.e. light data or material name) to the object names to help you keep track of which objects are using the same light data. Shift-clicking it does the opposite, renaming objects to match the data name.
Visibility		Hide the light from both the viewport and the render with this toggle.
Select		Select only this light and make it the active object.
Solo		Temporarily hide all other lights, allowing you to see the effect of this light alone. While in Solo mode, you can show other lights one at a time as well. When you exit Solo mode, your previous arrangement of light visibility will be restored.
Type		An icon showing the type of this light (Eg. area, sun, mesh…). Click this icon to change the type.
Strength		A slider for the power or intensity of the light. You can also manually choose a node in the Node Editor (properties region/"N-panel") to use for the strength slider. The first unconnected Value input socket will be chosen. The -/+ buttons decrease and increase the light power in increments, hold Shift for smaller increments, or Ctrl for larger ones.
Color		The color of the light, which can be the unconnected Emission shader color, or Blackbody Temperature, Wavelength, Image or RGB node if they are connected to the shader.
Size		The Virtual size of the lamp, determining the softness of the shadow and the falloff of the light across and around surfaces.
Samples	Cycles Branched Path Tracing, or Blender Render	The number of iterations to calculate the shadow of the light, to reduce the noise it introduces.
Shadow Method	Blender Render only	Choose between No Shadow, Buffer Shadow and Ray Traced Shadows.
MIS	Cycles only	Toggle Multiple Importance Sampling for this light.
Shadow	Cycles only	Choose whether or not the light casts shadows.
Diff		Allow the light to influence diffuse shaders
Spec		Allow the light to influence glossy shaders (or the specular calculation in Blender Render)
Cam	Cycles only, on mesh lights	Allow the mesh itself to be seen in the render, or to be invisible.
Spot Size	Spot lamps	The angle of the spot lamp’s influence
Blend	Spot lamps	The softness of the edge of the spot lamp’s influence
Falloff	Cycles, or Blender Render Point/Spot light	The rate at which the light loses intensity over distance.

World

Button	Context	Function
Visibility	Cycles only	Don’t show the world light in the render. This works by disabling all the ray influences of the world
Solo		Hide all other lights except the world. While in Solo mode, you can show other lights one at a time as well. When you exit Solo mode, your previous arrangement of light visibility will be restored.
Strength		A slider for the power or intensity of the world light. Unlike other lights, the node socket used for the world’s strength value is determined automatically.
Color		The color of the world’s Background shader. If an Image or Environment texture is connected somewhere in the chain, this is shown instead. Otherwise the first unconnected color socket of the leftmost node in the chain is shown. For Blender Render, if Blend Sky is enabled the Zenith color is shown here as well.
Blend Sky	Blender Render only	Make the background color a gradient from the horizon to the zenith.
Paper	if Blend Sky is enabled	Ensure the gradient is in camera-space, making it unaffected by perspective or camera angle.
Real	if Blend Sky is enabled	Render the background with a real horizon, affected by camera angle.
MIS	Cycles only	Calculate which areas of the background image emit the most light and sample these areas more often. Gives a large improvement on the amount of noise, but uses more memory. Not recommended for solid color backgrounds.
Refl Only	Cycles only	Only show the world in glossy rays, do not use it for lighting
Ambient Occlusion	Enable the world AO
Factor	if AO is enabled	How much AO influences the scene
Distance	if AO is enabled	The distance within which objects give an occlusion effect
Environment Lighting	Blender Render only	Enable Environment lighting - sort of like AO in Add mode, but coloured and without a distance option
Energy	if Environment Light is enabled	The strength of the Environment Light
Gather Method	Blender Render only	Choose whether the AO and Envrio Light is accurate and raytraced or faster but approximate.
Samples	Raytraced Gather	The number of calculations to perform, determines the amount of noise.
Passes	Approximate Gather	The number of preprocessing passes to reduce over-occlusion
Error Tolerance	Approximate Gather	The allowed difference between the approximate result and the accurate result. Lower values are better quality, but render slower.
Correction	Approximate Gather	A correction value for over-occlusion.
Link Sky Texture	Cycles	Link the vector of the sky texture to the rotation of an object (such as a sun lamp) so that the sky appearance is correct for the angle of the sun.

If the HDRI Handler is enabled, those settings will show here instead. Visibilty and Solo buttons will still be available.