left panel

From top to bottom:

Navigate and zoom the center view.
Take and view snapshots for comparison with the current edit.
duplicate manager
View and manage duplicates.
global color picker
Select and display color information taken from parts of the image.
image information
Display information about the current image.
mask manager
View and edit drawn shapes.

right panel

From top to bottom:

A graphical depiction of the image’s light levels and colors. This module can be moved to the left-hand panel if desired (see preferences > miscellaneous > position of the scopes module).
module groups
Select module groups (if enabled).
search module
Search for a module (if enabled).
processing modules
The modules used to process an image.
module order
Choose the order in which processing modules are executed in the pixelpipe.

bottom panel


From left to right:

Quick access menu for styles. Hover over a style name with your mouse to show a preview of the current darkroom image with the selected style applied.
color assessment
Toggle the ISO12646 color assessment view.
raw overexposed warning
Toggle raw overexposed indicators (right-click for options).
clipping warning
Toggle clipping warnings (right-click for options).
soft proof
Toggle softproofing overlays (right-click for options).
gamut check
Toggle gamut checking (right-click for options).
guides & overlays
Left-click to switch global guide overlays on/off and right-click to change the guide settings, including the color of all on-image drawing (masks, crop guides etc.)

You can also enable the filmstrip module at the bottom of the screen to allow you select and interact with the currently selected collection in the lighttable view.