The emacs help system is always available. With the default key bindings, you can start it with CONTROL-H. The help system then prompts you for a one-letter help command. If you do not know which help command you want, type ? or CONTROL-H to switch the current window to a list of help commands, each with a one-line description; emacs again requests a one-letter help command. If you decide you do not want help after all, type CONTROL-G to cancel your help request and return to the former buffer.
If the help output is only a single line, it appears in the Echo Area. If it consists of more text, the output appears in its own window. Use CONTROL-V and META-v to scroll forward and backward through the buffer (page 210). You can move the cursor between windows with CONTROL-X o (lowercase "o"). See page 225 for a discussion on working with multiple windows.
Tip: Closing the help window
To delete the help window while the cursor is in the window that holds the text you are editing, type CONTROL-X 1 (one). Alternatively, you can move the cursor to the help window (CONTROL-X 0 [lowercase "o"]) and type CONTROL-X 0 (zero) to delete the current window.
If help displays a window that occupies the entire screen, as is the case with CONTROL-H n (emacs news) and CONTROL-H t (emacs tutorial), you can kill the help buffer with CONTROL-X k or use CONTROL-X b to switch buffers (both on page 224).
On many terminals the BACKSPACE or LEFT ARROW key generates CONTROL-H. If you forget that you are using emacs and try to back over a few characters, you may unintentionally enter the help system. This action does not pose a danger to the buffer you are editing, but it can be unsettling to lose the window contents and not have a clear picture of how to restore it. While you are being prompted for the type of help you want you can type CONTROL-G to remove the prompt and return to editing the buffer. Some users elect to put help on a different key (page 240). Table 7-3 lists some of the help commands.
As this abridged presentation makes clear, you can use the help system to browse through the emacs internal Lisp system. For the curious following is Stallman's list of strings that match many names in the Lisp system. To get a view of the internal functionality of emacs, you can use any of these strings with CONTROL-H a (help system list of commands) or META-x apropos (prompts for a string and lists variables whose names contain that string).