diff --git a/developer_manual/digging_deeper/index.rst b/developer_manual/digging_deeper/index.rst
index 004f2b4b6..9d289d2d3 100644
--- a/developer_manual/digging_deeper/index.rst
+++ b/developer_manual/digging_deeper/index.rst
@@ -24,4 +24,5 @@ Digging deeper
    two-factor-provider
    users
    dashboard
+   projects
    web_host_metadata
diff --git a/developer_manual/digging_deeper/projects.rst b/developer_manual/digging_deeper/projects.rst
new file mode 100644
index 000000000..b47f16ef1
--- /dev/null
+++ b/developer_manual/digging_deeper/projects.rst
@@ -0,0 +1,216 @@
+========
+Projects
+========
+
+Projects are a way to link items from different apps via a common interface.
+
+App developers can integrate into projects and provide their own entity types to link with.
+
+
+Register a resource provider
+---------------------------
+
+Things like files, deck cards and talk rooms are called Resources in projects.
+In order to add your own resource type, we need to create a class implementing the
+`OCP\Collaboration\Resources\IProvider` interface.
+
+.. code-block:: php
+
+    <?php
+
+    namespace OCA\MyApp\Collaboration\Resources;
+
+
+    use OCP\Collaboration\Resources\IProvider;
+    use OCP\Collaboration\Resources\IResource;
+    use OCP\IURLGenerator;
+    use OCP\IUser;
+
+    class MyResourceProvider implements IProvider {
+        public const RESOURCE_TYPE = 'my-app-item';
+
+        /**
+         * @var IURLGenerator
+         */
+        private $url;
+
+        public function __construct(IURLGenerator $url) {
+            $this->url = $url;
+        }
+
+        /**
+         * @inheritDoc
+         */
+        public function getType(): string {
+            return self::RESOURCE_TYPE;
+        }
+
+        /**
+         * @inheritDoc
+         */
+        public function getResourceRichObject(IResource $resource): array {
+            $item = $this->getItem($resource);
+            $icon = $this->url->linkToRouteAbsolute('myapp.images.get_icon', ['id' => $item->getId()]);
+            $resourceUrl = $this->url->linkToRouteAbsolute('bookmarks.page.index', ['item' => $bookmark->getId()]);
+
+            return [
+                'type' => self::RESOURCE_TYPE,
+                'id' => $resource->getId(),
+                'name' => $item->getTitle(),
+                'link' => $resourceUrl,
+                'iconUrl' => $favicon,
+            ];
+        }
+
+        /**
+         * @inheritDoc
+         */
+        public function canAccessResource(IResource $resource, ?IUser $user): bool {
+            if ($resource->getType() !== self::RESOURCE_TYPE || !($user instanceof IUser)) {
+                return false;
+            }
+            $bookmark = $this->getItem($resource);
+            if ($bookmark === null) {
+                return false;
+            }
+            return $bookmark->getUserId() === $user->getUID()
+        }
+
+        private function getItem(IResource $resource) : ?Item {
+            // implement me
+        }
+    }
+
+
+The `MyResourceProvider` class needs to be registered during the :ref:`app bootstrap<Bootstrapping>`.
+
+.. code-block:: php
+
+    <?php
+
+    declare(strict_types=1);
+
+    namespace OCA\MyApp\AppInfo;
+
+    use OCP\AppFramework\App;
+    use OCP\AppFramework\Bootstrap\IBootContext;
+    use OCP\AppFramework\Bootstrap\IBootstrap;
+    use OCP\AppFramework\Bootstrap\IRegistrationContext;
+    use OCA\MyApp\Dashboard\MyAppWidget;
+
+    class Application extends App implements IBootstrap {
+
+        public const APP_ID = 'myapp';
+
+        public function __construct(array $urlParams = []) {
+            parent::__construct(self::APP_ID, $urlParams);
+        }
+
+        public function register(IRegistrationContext $context): void {
+        }
+
+        public function boot(IBootContext $context): void {
+            $context->injectFn(Closure::fromCallable([$this, 'registerCollaborationResources']));
+        }
+
+        protected function registerCollaborationResources(IProviderManager $resourceManager, SymfonyAdapter $symfonyAdapter): void {
+            $resourceManager->registerResourceProvider(ResourceProvider::class);
+
+            $symfonyAdapter->addListener('\OCP\Collaboration\Resources::loadAdditionalScripts', static function () {
+                Util::addScript(self::APP_ID, 'collections');
+            });
+        }
+    }
+
+As you can see we also already register a front-end script, which we are going to create next.
+
+
+Provide a user interface
+------------------------
+
+The user interface can be registered through the public `OCP.Collaboration.registerType`
+JavaScript method. The first parameter represents the resource type that has already
+been specified in the `IResourceProvider` implementation. The second parameter is an object with
+three properties:
+
+  * `typeString` A localized string that will be displayed in the dropdown when choosing which resource type to link to
+  * `typeIconClass` A CSS class of the icon that should be used for this entry
+  * `action` An async function that will produce a resource picker UI and resolves with the resource id
+
+The following example shows how a Vue.js component could be used to render the
+widget user interface, however this approach works for any other framework as well
+as plain JavaScript:
+
+
+.. code-block:: javascript
+
+        import Vue from 'vue'
+        import ItemPickerDialog from './components/ItemPickerDialog'
+
+    	OCP.Collaboration.registerType('myapp', {
+		action: () => {
+			return new Promise((resolve, reject) => {
+				const container = document.createElement('div')
+				container.id = 'myapp-item-select'
+				const body = document.getElementById('body-user')
+				body.appendChild(container)
+				const ComponentVM = new Vue({
+					render: h => h(ItemPickerDialog),
+				})
+				ComponentVM.$mount(container)
+				ComponentVM.$root.$on('close', () => {
+					ComponentVM.$el.remove()
+					ComponentVM.$destroy()
+					reject(new Error('User cancelled resource selection'))
+				})
+				ComponentVM.$root.$on('select', (id) => {
+					resolve(id)
+					ComponentVM.$el.remove()
+					ComponentVM.$destroy()
+				})
+			})
+		},
+		typeString: t('myapp', 'Link to an item'),
+		typeIconClass: 'icon-file',
+	})
+
+This will allow other apps to link to your items. We also want to link to other apps' items.
+Since all apps with projects support are listening on the above loadAdditionalScripts event,
+we can simply dispatch it when we render our main page template.
+
+.. code-block:: php
+
+    \OC::$server->getEventDispatcher()->dispatch('\OCP\Collaboration\Resources::loadAdditionalScripts');
+
+In our Vue app, we can then render the pre-built projects picker available in the npm package `nextcloud-vue-collections`.
+
+.. code-block:: vue
+
+    <template>
+        <div>
+            <CollectionList v-if="itemId"
+                :id="itemId"
+                :name="itemTitle"
+                type="myapp" />
+        </div>
+    </template>
+
+    <script>
+    import { CollectionList } from 'nextcloud-vue-collections'
+    export default {
+        name: 'CollaborationView',
+        components: {
+            CollectionList,
+        },
+        props: {
+            id: {
+                type: String,
+                default: '',
+            },
+            name: {
+                type: String,
+                default: '',
+            }
+        }
+    }
+    </script>