diff --git a/README.md b/README.md
index 70c649f..e338c33 100644
--- a/README.md
+++ b/README.md
@@ -16,11 +16,21 @@ The screen is divided into two panels:
   graph.
 * The visualization, on the right, where the results are displayed.
 
+### Object types
+
+* A *node* is the fundamental unit in Architype, usually representing a server,
+  service, or process step.
+* A *link* is connects nodes together. All links in Architype are directional,
+  i.e. they have an arrow at exactly one end.
+* A *group* is a collection of nodes that are physically together.
+* A *label* is an optional description of another object, e.g. a link or a
+  group.
+
 ### Keys
 
 Generally lowercase and uppercase versions of a key have related but opposite
 functions, for some meaning of "opposite". For example, lowercase `n` creates a
-new node line below the current line, while uppercase `n` (`shift` + `n`)
+new node line below the current line, while uppercase `N` (`shift` + `n`)
 creates a new node line above the current line.
 
 Limited vi key mappings are supported. Keys behavior is expected to match user
@@ -32,3 +42,29 @@ expectation across contexts in the UI.
 * `↑` `k` Move up the current list
 * `→` `l` `⏎` Enter (edit) the current list or item
 * `←` `h` `␛` Exit the current list or item
+
+#### New objects
+
+* `n` Create new node below the current line
+* `shift` + `n` Create new node above the current line
+* `g` Create new group below the current line
+* `shift` + `g` Create new group above the current line
+* `i` Create new link below the current line
+* `shift` + `i` Create new link above the current line
+* `a` Create new label below the current line
+* `shift` + `a` Create new label above the current line
+
+#### Deletion & modification
+
+* `d` Delete the current line
+* `shift` + `d` Delete the current line and all lines after it
+* `␣` (`space`) Toggle highlighting of the current line
+* `f` [link only] Flip the directional of the current link
+
+#### Misc
+
+* `u` `browser back` Undo the last action
+* `U` `browser forward` Redo the last undone action (if nothing else has been
+  done since then)
+* `m` Select the next theme (light/dark)
+* `M` Select the previous theme (light/dark)