Below is a list of some useful terms we use with regard to Atom.
A buffer is the text content of a file in Atom. It's basically the same as a file for most descriptions, but it's the version Atom has in memory. For instance, you can change the text of a buffer and it isn't written to its associated file until you save it.
A command is a bit of functionality in Atom that can be triggered by the user either through a keybinding or a menu item.
Docks are collapsible pane containers that attach to the left, right, and bottom sides of the Atom window.
A key combination is some combination or sequence of keys that are pressed to perform a task.
A key sequence is a special case of a key combination. It is a key combination that consists of keys that must be pressed and released in sequence. Ctrl+K Down is a key sequence. Alt+S is not a key sequence because it is two keys that are pressed and released together rather than in succession.
A keybinding is the mapping of a key combination, such as Ctrl+Enter to an Atom command.
A keymap is a collection of keybindings. It can also refer to a file or files containing keybindings for an Atom package or Atom itself.
An Atom plugin. There is a bunch more information in the section on Atom Packages.
A pane is a visual section of the editor space. Each pane can hold multiple pane items. There is always at least one pane in each Atom window.
A section of the Atom UI that can contain multiple panes.
Some item, often an editor, that is displayed within a pane. In the default configuration of Atom, pane items are represented by tabs at the top of each pane.
Note: The reason why we don't call them "tabs" is because you can disable the tabs package and then there aren't any tabs. For a similar reason, we don't call them files because some things can be shown in a pane that aren't files, like the Settings View.
A piece of the Atom UI that is outside the editor space.