^ = Ctrl key
M = Alt key
^G (F1) Display this help text
^X (F2) Close the current file buffer / Exit from nano
^O (F3) Write the current file to disk
^J (F4) Justify the current paragraph
^R (F5) Insert another file into the current one
^W (F6) Search for a string or a regular expression
^Y (F7) Move to the previous screen
^V (F8) Move to the next screen
^K (F9) Cut the current line and store it in the cutbuffer
^U (F10) Uncut from the cutbuffer into the current line
^C (F11) Display the position of the cursor
^T (F12) Invoke the spell checker, if available
^_ (F13) (M-G) Go to line and column number
^\ (F14) (M-R) Replace a string or a regular expression
^^ (F15) (M-A) Mark text at the cursor position
(F16) (M-W) Repeat last search
M-^ (M-6) Copy the current line and store it in the cutbuffer
M-} Indent the current line
M-{ Unindent the current line
^F Move forward one character
^B Move back one character
^Space Move forward one word
M-Space Move back one word
^P Move to the previous line
^N Move to the next line
^A Move to the beginning of the current line
^E Move to the end of the current line
M-( (M-9) Move to the beginning of the current paragraph
M-) (M-0) Move to the end of the current paragraph
M-\ (M-|) Move to the first line of the file
M-/ (M-?) Move to the last line of the file
M-] Move to the matching bracket
M-- (M-_) Scroll up one line without scrolling the cursor
M-+ (M-=) Scroll down one line without scrolling the cursor
M-< (M-,) Switch to the previous file buffer
M-> (M-.) Switch to the next file buffer
M-V Insert the next keystroke verbatim
^I Insert a tab at the cursor position
^M Insert a newline at the cursor position
^D Delete the character under the cursor
^H Delete the character to the left of the cursor
M-T Cut from the cursor position to the end of the file
M-J Justify the entire file
M-D Count the number of words, lines, and characters
^L Refresh (redraw) the current screen
M-X Help mode enable/disable
M-C Constant cursor position display enable/disable
M-O Use of one more line for editing enable/disable
M-S Smooth scrolling enable/disable
M-P Whitespace display enable/disable
M-Y Color syntax highlighting enable/disable
M-H Smart home key enable/disable
M-I Auto indent enable/disable
M-K Cut to end enable/disable
M-L Long line wrapping enable/disable
M-Q Conversion of typed tabs to spaces enable/disable
M-B Backup files enable/disable
M-F Multiple file buffers enable/disable
M-M Mouse support enable/disable
M-N No conversion from DOS/Mac format enable/disable
M-Z Suspension enable/disable
very useful, gives extra power.
Though most prefer Vi, but without a backup text editor like nano, things are always guaranteed to work out.