Some very useful shorcuts
C-x C-f # Open a file
C-x k # Close buffer
C-x C-s # Save single file
C-x C-c # Exit
C-x b # Cycle buffers
M-x untabify # Remove all tab characters in the selected region
Encoding
C-x RET f unix # Set encoding to unix
Selection and editting
C-spc direction # Start selection
C-w # Cut
M-w # Copy
C-y # Paste
M-x replace-string # Replace all occurences of a string
M-x query-replace # Replace matched strings one-by-one
C-q C-j # Insert a newline in the search or replace string
Rectangles
C-x r t # Set text in the selected rectangle
C-x r d # Delete text in the selected rectangle
C-x r k # Cut the rectangular region
C-x r M-w # Copy the rectangular region
C-x r y # Paste the rectangular region (yank)
Webmode shortcuts
C-c C-i # Indent all code
C-c C-f # Toggle folding
Keyboard Macro
Eg: Appending characters to the end of each line in Emacs
C-x ( C-e a C-n C-x )