diff --git a/README.md b/README.md
index 6d17b8153..5b83bd247 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,51 @@ This software is licensed under the [Apache License][5].
 
 This software has no bugs. You can dispute this statement at [bugzilla][3]
 
+## Code Structure ##
+
+Key breakdowns:
+
+Activities started within the UI:
+* ContributionsActivity (ContributionsListFragment, MediaDetailPagerFragment, MediaDetailFragment) - main "my uploads" list and detail view
+* LoginActivity - login screen when setting up an account
+* SettingsActivity - settings screen
+* AboutActivity - about screen
+
+Activities receiving intents:
+* ShareActivity (SingleUploadFragment, CategorizationFragment) - handles receiving a file from another app, accepting a title/desc, and slating it for upload
+* MultipleShareActivity (MultipleUploadListFragment, CategorizationFragment) - handles receiving a batch of multiple files from another app, accepting a title/desc, and slating them for upload
+
+Services:
+* WikiAccountAuthenticatorService - authentication service
+* UploadService - performs actual file uploads in background
+* ContributionsSyncService - polls for updated contributions list from server
+* ModificationsSyncService - pushes category additions up to server
+
+Content providers:
+* ContributionsContentProvider - private storage for local copy of user's contribution list
+* ModificationsContentProvider - private storage for pending category and template modifications
+* CategoryContentProvider - private storage for recently used categories
+
+
+## On-Device Storage ##
+
+Account credentials are encapsulated in an account provider. Currently only one Wikimedia Commons account is supported at a time. (Question: what is the actual storage for credentials?)
+
+Preferences are stored in Android's SharedPreferences.
+
+Information about past and pending uploads is stored in the Contributions content provider, which uses an SQLite database on the backend.
+
+A list of recently-used categories is stored in the Categories content provider, which uses an SQLite database on the backend.
+
+Captured files are not currently stored within the app, but are passed by content: or file: URI from other apps.
+
+Thumbnail images are not currently cached. (?)
+
+
+
+
+
+
 [1]: https://developer.android.com/sdk/index.html
 [2]: https://maven.apache.org/
 [3]: https://bugzilla.wikimedia.org/enter_bug.cgi?product=Commons%20App