diff --git a/README.md b/README.md
index 99dd883..63dee3e 100644
--- a/README.md
+++ b/README.md
@@ -5,24 +5,19 @@
 
 ## About
 
-mood-line is a minimal mode line configuration that aims to replicate some of the features of the
-more advanced [doom-modeline](https://github.com/seagle0128/doom-modeline) package.
+mood-line is a lightweight, drop-in replacement for the default Emacs mode line configuration.
 
 ## Features
 
-* Clean, minimal design
+* Clean, informative design
+
+* Customizable, modular segment format
 
 * Customizable glyph sets
 
-* Anzu and multiple-cursors counters
+* Lazy-loaded extensions
 
-* Encoding and EOL style indicator
-
-* Version control status indicator
-
-* Custom Flycheck/Flymake indicator
-
-* Lightweight with no dependencies
+* Lightweight, no dependencies
 
 ## Preview
 
@@ -48,6 +43,40 @@ If you are a user of `use-package`, it is easy to configure mood-line directly i
   (mood-line-glyph-alist . mood-line-glyphs-fira-code))
 ```
 
+### Format
+
+mood-line uses a modular segment format, and it is easy to reconfigure:
+
+```elisp
+;; Default format:
+;;   * init.el  4:32 Top                                         ELisp  ! Issues: 2
+(setq mood-line-format mood-line-format-default)
+
+;; Extended format:
+;;   * init.el  4:32:52 Top                    SPCx2  LF  UTF-8  ELisp  ! Issues: 2
+(setq mood-line-format mood-line-format-default-extended)
+
+;; Custom format:
+;;   * init.el : ELisp                                     Top 4:32  |  ! Issues: 2
+(setq mood-line-format
+      '(;; Left side
+        (" "
+         (mood-line-segment-buffer-status) " "
+         (mood-line-segment-buffer-name) " : "
+         (mood-line-segment-major-mode))
+        ;; Right side
+        ((mood-line-segment-scroll) " "
+         (mood-line-segment-cursor-position) "  "
+         (when (mood-line-segment-checker) "|") "  "
+         (mood-line-segment-checker) "  "
+         " ")))
+```
+
+More information on the format specification is available in the documentation.
+(`M-x describe-variable mood-line-format`)
+
+### Glyphs
+
 By default, mood-line will use basic ASCII character glyphs to decorate mode line segments.
 If you'd like to see prettier Unicode glyphs, you can change the value of `mood-line-glyph-alist`:
 
@@ -72,6 +101,14 @@ If you'd like to supply your own glyphs, you can use the customization interface
 You can further tweak the behavior and appearance of mood-line by viewing the customizable variables
 and faces in the `mood-line` and `mood-line-faces` customization groups. (`M-x customize-group mood-line`)
 
+## Testing
+
+To run the included tests:
+
+```bash
+./ert-test.sh
+```
+
 ## Feedback
 
 If you experience any issues with this package, please