Info: (elisp) Visiting Files

elisp: Visiting Files

 
 24.1 Visiting Files
 ===================
 
 Visiting a file means reading a file into a buffer.  Once this is done,
 we say that the buffer is “visiting” that file, and call the file “the
 visited file” of the buffer.
 
    A file and a buffer are two different things.  A file is information
 recorded permanently in the computer (unless you delete it).  A buffer,
 on the other hand, is information inside of Emacs that will vanish at
 the end of the editing session (or when you kill the buffer).  When a
 buffer is visiting a file, it contains information copied from the file.
 The copy in the buffer is what you modify with editing commands.
 Changes to the buffer do not change the file; to make the changes
 permanent, you must “save” the buffer, which means copying the altered
 buffer contents back into the file.
 
    Despite the distinction between files and buffers, people often refer
 to a file when they mean a buffer and vice-versa.  Indeed, we say, “I am
 editing a file”, rather than, “I am editing a buffer that I will soon
 save as a file of the same name”.  Humans do not usually need to make
 the distinction explicit.  When dealing with a computer program,
 however, it is good to keep the distinction in mind.
elisp: Visiting Files

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