diff --git a/doc/user/admin_area/diff_limits.md b/doc/user/admin_area/diff_limits.md
index 9fe4b50a99130ee36d24a19c91476eaae2c6e9cf..5117b5f476f17eb1dcfeb0f518f6bc212676d4a9 100644
--- a/doc/user/admin_area/diff_limits.md
+++ b/doc/user/admin_area/diff_limits.md
@@ -6,6 +6,8 @@ type: reference
 
 You can set a maximum size for display of diff files (patches).
 
+For details about diff files, [View changes between files](../project/merge_requests/index.md#view-changes-between-file-versions).
+
 ## Maximum diff patch size
 
 Diff files which exceed this value will be presented as 'too large' and won't
diff --git a/doc/user/project/merge_requests/img/merge_request_diff_v12_2.png b/doc/user/project/merge_requests/img/merge_request_diff_v12_2.png
new file mode 100644
index 0000000000000000000000000000000000000000..e56fbb9750fec4b346e895d9459cb95252264ce2
Binary files /dev/null and b/doc/user/project/merge_requests/img/merge_request_diff_v12_2.png differ
diff --git a/doc/user/project/merge_requests/index.md b/doc/user/project/merge_requests/index.md
index 9f31f38460abc736931b310f2056889f515e382d..4e79d66df478323773b89bb12104b3d5475e831b 100644
--- a/doc/user/project/merge_requests/index.md
+++ b/doc/user/project/merge_requests/index.md
@@ -164,6 +164,26 @@ you hide threads that are no longer relevant.
 
 [Read more about resolving threads in merge requests reviews.](../../discussions/index.md)
 
+## View changes between file versions
+
+The **Changes** tab of a merge request shows the changes to files between branches or
+commits. This view of changes to a file is also known as a **diff**. By default, the diff view
+compares the file in the merge request branch and the file in the target branch.
+
+The diff view includes the following:
+
+- The file's name and path.
+- The number of lines added and deleted.
+- Buttons for the following options:
+  - Toggle comments for this file; useful for inline reviews.
+  - Edit the file in the merge request's branch.
+  - Show full file, in case you want to look at the changes in context with the rest of the file.
+  - View file at the current commit.
+  - Preview the changes with [Review Apps](../../../ci/review_apps/index.md).
+- The changed lines, with the specific changes highlighted.
+
+![Example screenshot of a source code diff](img/merge_request_diff_v12_2.png)
+
 ## Commenting on any file line in merge requests
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/13950) in GitLab 11.5.