An Emacs object containing a document or application view. It is not necessarily a file, and switching buffers does not close the one you leave. A window displays a buffer. See Buffers hold your work.
A view of a buffer inside an Emacs frame. Removing a window does not kill its buffer. Two windows showing the same buffer are views of the same text, not independent copies. See Working with windows.
An outer Emacs application window, or the corresponding display in a terminal session. It contains Emacs windows. Selecting another window within a frame differs from switching applications in the operating system. See Windows and frames.
The current editing position, between characters. Text is normally inserted there. Short reading often leaves it unchanged; tracked reading advances it. See Reading position and interruption.
The commands and behaviour associated with a buffer. Its major mode supplies its principal tools; minor modes add other behaviour. See Let modes give each buffer its tools.
A buffer state that prevents ordinary text edits. It does not mean the buffer has no unsaved changes, and making a buffer writable does not grant permission to overwrite a protected file. Special applications may still provide their own operations. See Opening a document safely.
Restricting access to part of a buffer without deleting the rest. Reading, movement and many editing commands stay within that portion; widening removes the restriction. Ordinary file saving still saves the entire buffer. See Reading accessible text and Narrowing in the GNU Emacs Manual.
The buffer and position retained when a settings workflow starts. Contextual actions continue to refer to that source rather than whichever menu or editor is currently selected. A changed or closed source may need to be captured again. See Getting started with settings menus.
Where a setting or rule applies, such as one buffer, a session, or global defaults. Scope is not the same as persistence: a global change need not be saved, and a saved resource need not be active. See Choose what persists.