Important Keyboard Shortcuts

Ctrl .    (that's  the keys Ctrl, and the . key at the same time)
    Extend selection to a larger sub expression, the whole cell, group  of cells, ... ,all cells.  This is about the only way to select a cell when  the CellBracket isn't shown!

Ctrl a

Select ALL cells in the selected notebook.

Ctrl Shift [    (that's the keys Ctrl, Shift, [  at the same time)
Open ALL selected cells.

Ctrl Shif E  (that's the keys Ctrl, Shift, E  at the same time)
Switch the current cell between normal and the underlying box  structure.

Ctrl Shift ]

Close ALL selected cells

Ctrl K  (with something selected)
Complete the selection
Examples:  "Work Ctrl k" →  WorkingPrecision
                 "\[Contour Ctrl k" →  ∮  )

Created by Mathematica  (May 17, 2004)