Ctrl+a c        new window
Ctrl+a n        next window
Ctrl+a p        previous window
Ctrl+a "        select window from list
Ctrl+a Ctrl+a   previous window viewed

Ctrl+a A        set window title
Ctrl+a <no>     goto window number
Ctrl+a :number <no>
                renumber current window

Ctrl+a S        split terminal horizontally into regions
Ctrl+a |        split terminal vertically into regions  Requires screen >= 4.1
Ctrl+a :resize  resize region
Ctrl+a :fit     fit screen size to new terminal size    Ctrl+a F is the same. Do after resizing xterm
Ctrl+a :remove  remove region   Ctrl+a X is the same
Ctrl+a tab      Move to next region

Ctrl+a d        detach screen from terminal Start screen with -r option to reattach
Ctrl+a x        lock session    Enter user password to unlock
Ctrl+a [        enter scrollback/copy mode  Enter to start and end copy region. Ctrl+a ] to leave this mode
Ctrl+a ]        paste buffer    Supports pasting between windows
Ctrl+a >        write paste buffer to file  useful for copying between screens
Ctrl+a <        read paste buffer from file useful for pasting between screens

Ctrl+a ?        show key bindings/command names Note unbound commands only in man page
Ctrl+a :        goto screen command prompt  up shows last command entered