2- Scene Browser
Scene Browser lists all elements in the scene and shows a clear tree structure of the model, where you can view parent / child relationships.
When selecting a parent in the Scene Browser and hide it or delete, the effect is automatically applied to all its children so they are automatically hidden or deleted.
Scene Browser allows using Shift or Ctrl to select many items in the object browser.
Changing parent / child relation ship in Scene Browser can be done easily by dragging an object or group off objects and dropping them in a new parent
Environment on top of the tree, unlike other elements, environment always exists and you can not delete it. When you click on Environment in the Scene browser, Properties Panel is updated to show the properties on the environment, which allows you to make many changes to the environment.
Selecting object(s), then right clicking, shows a helping menu allowing quick actions like Hide/Show object(s), Change parent, Add parent, or perform a geometry operation.
Scene Browser uses icons to identify the object types, but even with icons for large scenes it may not be easy to find the object(s) you are looking for, for helping in this task Scene Browser provides two options
Scene Browser Filters: you can select filter to show only object(s) of specific types, for example you can view all Lights in the scene by selecting the Light filter