diff --git a/src/Entity/EntityBrowser.php b/src/Entity/EntityBrowser.php
index fc61c91..3961bf9 100644
--- a/src/Entity/EntityBrowser.php
+++ b/src/Entity/EntityBrowser.php
@@ -9,6 +9,7 @@
 
 use Drupal\Core\Config\Entity\ConfigEntityBase;
 use Drupal\Core\Entity\EntityWithPluginBagsInterface;
+use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\DefaultPluginBag;
 use Drupal\Core\Plugin\DefaultSinglePluginBag;
 use Drupal\entity_browser\EntityBrowserInterface;
@@ -251,4 +252,61 @@ public function getWidgetSelector() {
     return $this->widgetSelectorPluginBag()->get($this->widget_selector);
   }
 
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getSelectedEntities() {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setSelectedEntities(array $entities) {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function addSelectedEntities(array $entities) {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function selectionCompleted() {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    // @TODO Implement it.
+  }
+
 }
diff --git a/src/EntityBrowserDisplayInterface.php b/src/EntityBrowserDisplayInterface.php
index 2cbc022..bf7d4e1 100644
--- a/src/EntityBrowserDisplayInterface.php
+++ b/src/EntityBrowserDisplayInterface.php
@@ -22,4 +22,25 @@ interface EntityBrowserDisplayInterface extends PluginInspectionInterface {
    */
   public function label();
 
+  /**
+   * Displays entity browser.
+   *
+   * This is the "entry point" for every non-entity browser code to interact
+   * with it. It will take care about displaying entity browser in one way or
+   * another.
+   *
+   * @return array
+   *   An array suitable for drupal_render().
+   */
+  public function displayEntityBrowser();
+
+  /**
+   * Indicates completed selection.
+   *
+   * Entity browser will call this function when selection is done. Display
+   * plugin is responsible for fetching selected entities and sending them to
+   * the initiating code.
+   */
+  public function selectionCompleted();
+
 }
diff --git a/src/EntityBrowserInterface.php b/src/EntityBrowserInterface.php
index 164eed7..823c35e 100644
--- a/src/EntityBrowserInterface.php
+++ b/src/EntityBrowserInterface.php
@@ -8,11 +8,12 @@
 namespace Drupal\entity_browser;
 
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
+use Drupal\Core\Form\FormInterface;
 
 /**
  * Provides an interface defining an entity browser entity.
  */
-interface EntityBrowserInterface extends ConfigEntityInterface {
+interface EntityBrowserInterface extends ConfigEntityInterface, FormInterface {
 
   /**
    * Returns the entity browser name.
@@ -97,4 +98,36 @@ public function getSelectionDisplay();
    */
   public function getWidgetSelector();
 
+  /**
+   * Returns currently selected entities.
+   *
+   * @return array
+   *   Array of currently selected entities.
+   */
+  public function getSelectedEntities();
+
+  /**
+   * Sets currently selected entities.
+   *
+   * @param array $entities
+   *   Entities that are currently selected.
+   */
+  public function setSelectedEntities(array $entities);
+
+  /**
+   * Adds entities to currently selected entities.
+   *
+   * @param array $entities
+   *   Entities to be added to the list of currently selected entities.
+   */
+  public function addSelectedEntities(array $entities);
+
+  /**
+   * Indicates completed selection.
+   *
+   * Selection process is done and currently selected entities are sent to the
+   * initiating code.
+   */
+  public function selectionCompleted();
+
 }
diff --git a/src/EntityBrowserSelectionDisplayInterface.php b/src/EntityBrowserSelectionDisplayInterface.php
index 53c05b6..f873631 100644
--- a/src/EntityBrowserSelectionDisplayInterface.php
+++ b/src/EntityBrowserSelectionDisplayInterface.php
@@ -22,4 +22,12 @@ interface EntityBrowserSelectionDisplayInterface extends PluginInspectionInterfa
    */
   public function label();
 
+  /**
+   * Returns selection display form.
+   *
+   * @return array
+   *   Form structure.
+   */
+  public function getForm();
+
 }
diff --git a/src/EntityBrowserWidgetInterface.php b/src/EntityBrowserWidgetInterface.php
index c6470b2..c4ff0ca 100644
--- a/src/EntityBrowserWidgetInterface.php
+++ b/src/EntityBrowserWidgetInterface.php
@@ -30,4 +30,12 @@ public function label();
    */
   public function getWeight();
 
+  /**
+   * Returns widget form.
+   *
+   * @return array
+   *   Form structure.
+   */
+  public function getForm();
+
 }
diff --git a/src/EntityBrowserWidgetSelectorInterface.php b/src/EntityBrowserWidgetSelectorInterface.php
index 6721e8b..d12c61d 100644
--- a/src/EntityBrowserWidgetSelectorInterface.php
+++ b/src/EntityBrowserWidgetSelectorInterface.php
@@ -22,4 +22,20 @@ interface EntityBrowserWidgetSelectorInterface extends PluginInspectionInterface
    */
   public function label();
 
+  /**
+   * Returns widget selector form.
+   *
+   * @return array
+   *   Form structure.
+   */
+  public function getForm();
+
+  /**
+   * Returns ID of the widget that is currently selected.
+   *
+   * @return string
+   *   ID of the currently selected widget.
+   */
+  public function getCurrentWidget();
+
 }
diff --git a/src/Plugin/EntityBrowser/Display/Standalone.php b/src/Plugin/EntityBrowser/Display/Standalone.php
index d3d90fd..e37b983 100644
--- a/src/Plugin/EntityBrowser/Display/Standalone.php
+++ b/src/Plugin/EntityBrowser/Display/Standalone.php
@@ -33,4 +33,19 @@ class Standalone extends PluginBase implements EntityBrowserDisplayInterface {
   public function label() {
     return $this->label;
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function displayEntityBrowser() {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function selectionCompleted() {
+    // @TODO Implement it.
+  }
+
 }
diff --git a/src/Plugin/EntityBrowser/SelectionDisplay/NoDisplay.php b/src/Plugin/EntityBrowser/SelectionDisplay/NoDisplay.php
index 246898d..ec02aaf 100644
--- a/src/Plugin/EntityBrowser/SelectionDisplay/NoDisplay.php
+++ b/src/Plugin/EntityBrowser/SelectionDisplay/NoDisplay.php
@@ -34,4 +34,11 @@ public function label() {
     $this->label;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getForm() {
+    // @TODO Implement it.
+  }
+
 }
diff --git a/src/Plugin/EntityBrowser/Widget/View.php b/src/Plugin/EntityBrowser/Widget/View.php
index 9016f4d..d0ff00b 100644
--- a/src/Plugin/EntityBrowser/Widget/View.php
+++ b/src/Plugin/EntityBrowser/Widget/View.php
@@ -48,4 +48,11 @@ public function getWeight() {
     return $this->weight;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getForm() {
+    // @TODO Implement it.
+  }
+
 }
diff --git a/src/Plugin/EntityBrowser/WidgetSelector/Tabs.php b/src/Plugin/EntityBrowser/WidgetSelector/Tabs.php
index da15b7c..9b42a03 100644
--- a/src/Plugin/EntityBrowser/WidgetSelector/Tabs.php
+++ b/src/Plugin/EntityBrowser/WidgetSelector/Tabs.php
@@ -33,4 +33,19 @@ class Tabs extends PluginBase implements EntityBrowserWidgetSelectorInterface {
   public function label() {
     return $this->label;
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getForm() {
+    // @TODO Implement it.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCurrentWidget() {
+    // @TODO Implement it.
+  }
+
 }