Mathematica's interface is carefully optimized for both menu and keyboard use—with many convenient ergonomic features, including some that are not immediately visible from menus.
Multiple Click — select larger and larger subexpressions
Alt+[,
Alt+{,
Alt+( — enter matched brackets:
[],
{},
()
Ctrl+L — copy down an input line ()
Ctrl+Shift+L — copy down an output line ()
F1 — search for help on the name selected, or to the left
Shift+F1 — bring up a new instance of the help viewer
Shift+Ctrl+Enter — evaluate the selection in place
Shift+Ctrl+C — copy as plain text
Shift+Ctrl+P — print selection
Ctrl+' — toggle cell groups open/closed
Shift+Ctrl+{,
Shift+Ctrl+} — open/close all cell groups
Shift+Close — immediately close a notebook without saving
— create a new notebook, package, slide show, etc.
