diff --git a/static/source.html b/static/source.html
index 37ea6cbc..6e272026 100644
--- a/static/source.html
+++ b/static/source.html
@@ -28,10 +28,18 @@
                 <li><a href="https://github.com/GrapheneOS/branding_tools">Scripting for managing branding</a></li>
                 <li><a href="https://github.com/GrapheneOS/platform_manifest">Manifest for OS repositories</a></li>
             </ul>
-            <p>The operating system includes hundreds of repositories. The manifest repository
-            references all of these. Most of these are used unmodified from the Android Open
-            Source Project (AOSP). A few dozen of the repositories are either forked from AOSP or
-            are unique to GrapheneOS.</p>
+            <p>The operating system source tree includes hundreds of repositories. Many of these
+            are only used for debugging, testing or development and are not actually part of what
+            gets used for building a production release. The manifest repository references all of
+            these. Most of these are used unmodified from the Android Open Source Project (AOSP).
+            A few dozen of the repositories including most of the core OS are either forked from
+            AOSP or are unique to GrapheneOS. The operating system has a unified build system, but
+            some components like Chromium are too complex to fit into it so they're included as
+            prebuilts instead of porting them to the AOSP build system. This is also done for
+            developer convenience and bootstrapping, to avoid needing to build all the native /
+            cross-compilation toolchains for each host and target platform combination, etc. The
+            prebuilts can all be built from source if desired. The build instructions will be
+            expanded to cover all of this in the future.</p>
             <p>Chromium needs to be included in the GrapheneOS source tree as a prebuilt before
             building. The build metadata is in the <a href="https://github.com/GrapheneOS/chromium_build">
             chromium_build repository</a> and the GrapheneOS patches are in the