These toolbars are visible or available the Curve Editor is open, and in general contain controls for editing animation data in the form of function curves.
Two different Curve Editor layouts are available: standard and classic. The standard layout provides a streamlined interface designed for efficient function-curve editing, while the classic layout offers more tools by default in a familiar arrangement.
Curve Editor Toolbars: Standard Layout
The standard layout appears by default when you open Track View in Curve Editor mode, and displays the following toolbars:
Also, the standard layout has Filters 
Show Hierarchy off by default, while it's on in the classic layout.
To return to this layout from a different one, right-click an empty toolbar area and choose Load Layout Function Curve Layout.
Curve Editor Toolbars: Classic Layout
To access the classic layout, right-click an empty toolbar area and choose Load Layout Function Curve Layout (Classic). This layout includes these toolbars:
(upper toolbar)
(lower toolbar)
The Key Controls toolbar for the Curve Editor contains tools for moving and scaling keys, drawing curves, and inserting keys.
The Key Tangents toolbar lets you assign tangency to keys. Tangency controls the smoothness and the speed of motion near the key. For more information about tangents, see Tangent Types.
The Tangent Actions toolbar provides tools for unifying and breaking animation-key tangents.
The Keys toolbar for the Curve Editor contains tools for filtering tracks and transforming and editing keys.
The Curves toolbar provides controls for managing key selection and editing.
Tools on the Biped toolbar let you choose which animation curves to display in the Curve Editor. You can toggle between the position and rotation curves, as well as toggle the separate curves representing the X, Y, and Z axes of the current biped selection.
The Key Entry toolbar for the Curve Editor contains fields for editing individual keys from the keyboard. It appears by default in the standard Curve Editor, and is similar to the Key Stats toolbar.
