diff --git a/topics/basics/plugin_structure/plugin_extension_points.md b/topics/basics/plugin_structure/plugin_extension_points.md
index 0336d83c8..ce44c7d0d 100644
--- a/topics/basics/plugin_structure/plugin_extension_points.md
+++ b/topics/basics/plugin_structure/plugin_extension_points.md
@@ -1,7 +1,7 @@
-# Extension Points
-
 <!-- Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license. -->
 
+# Extension Points
+
 <link-summary>Allowing to extend plugin's functionality by other plugins.</link-summary>
 
 > See [Plugin Extensions](plugin_extensions.md) for _using_ extension points in your plugin.
@@ -57,6 +57,13 @@ Must be one of `IDEA_APPLICATION` for Application (default), `IDEA_PROJECT` for
 
 The plugin that contributes to the extension point will read those properties from the <path>plugin.xml</path> file.
 
+Base classes for extensions requiring a key:
+
+- [`LanguageExtension`](%gh-ic%/platform/core-api/src/com/intellij/lang/LanguageExtension.java)
+- [`FileTypeExtension`](%gh-ic%/platform/core-api/src/com/intellij/openapi/fileTypes/FileTypeExtension.java)
+- [`ClassExtension`](%gh-ic%/platform/core-api/src/com/intellij/openapi/util/ClassExtension.java)
+- [`KeyedExtensionCollector`](%gh-ic%/platform/core-api/src/com/intellij/openapi/util/KeyedExtensionCollector.java)
+
 > See [](bundling_plugin_openapi_sources.md) section explaining how to expose extension points sources to other plugins.
 >
 {style="note"}