Org mode

C-c C-, s	to insert begin end src code block
C-c ’	edit the current block in temp buffer, use the same command to exit
C-c a a	displays current Week or day agenda
C-c a t	displays todo list
C-c a c	displays agenda and todo list simultaneously

Elisp commands

C-M-x	to execute elisp function where point is anywhere in the function
C-u C-M-x	to execute elisp function where point is anywhere in the function and enable debug

<f3>	C-x (	start creating kbd macro
<f4>	C-x )	ends the macro creation
M-x name-last-kbd-macro		Give name to the recently created key board macro defined using <f3>
M-x insert-kbd-macro		Insert the macro with name in the current buffer

C-x u

visualize undo tree