diff --git a/index.html b/index.html
index bd461530e..eb5095282 100644
--- a/index.html
+++ b/index.html
@@ -201,6 +201,8 @@ <h2>
         </li>
         <li>[=manifest/theme_color=]
         </li>
+        <li>[=manifest/id=]
+        </li>
       </ul>
       <aside class="note">
         <p>
@@ -242,6 +244,7 @@ <h3>
                 "sizes": "128x128"
               }],
               "scope": "/",
+              "id": "superracer",
               "start_url": "/start.html",
               "display": "fullscreen",
               "orientation": "landscape",
@@ -808,6 +811,48 @@ <h3>
           </p>
         </section>
       </section>
+      <section>
+        <h3>
+          `id` member
+        </h3>
+        <p>
+          The [=manifest's=] <code><dfn data-export="" data-dfn-for=
+          "manifest">id</dfn></code> member is a <a>string</a> that
+          represents the <dfn>id</dfn> for the application. It is used by user
+          agents and third party entities to uniquely identify the application
+          globally.
+        </p>
+        <p>
+          To <dfn>process the `id` member</dfn>, given [=object=]
+          |json:JSON|, [=ordered map=] |manifest:ordered map|, and [=URL=]
+          |document URL:URL|:
+        </p>
+        <ol class="algorithm">
+          <li>If the type of |json|["id"] is not [=string=], return.
+          </li>
+          <li>If |json|["start_url"] is the empty string, return.
+          </li>
+          <li>Let |id:URL| be the result of [=URL Parser|parsing=]
+          |json|["id"], using the origin of <var>document URL</var> as the base URL.
+          </li>
+          <li>If |id| is failure, return.
+          </li>
+          <li>If |id| is not <a>same origin</a> as <var>document
+          URL</var>, return.
+          </li>
+          <li>Otherwise, set |manifest|["id"] to |start URL|.
+          </li>
+        </ol>
+        <aside class="example">
+          <p>
+            For example, if the value of [=manifest/start_url=] is
+            <samp>../start_point.html</samp>, and the manifest's URL is
+            <samp>https://example.com/resources/manifest.webmanifest</samp>,
+            then the result of [=URL parser|parsing=] would be
+            <samp>https://example.com/start_point.html</samp>.
+          </p>
+        </aside>
+      </section>
       <section>
         <h3>
           `theme_color` member
@@ -1084,6 +1129,9 @@ <h3>
             <li>[=Process the `start_url` member=] passing |json|, |manifest|,
             |manifest URL|, and |document URL|.
             </li>
+            <li>[=Process the `id` member=] passing |json|, |manifest| and
+            |document URL|.
+            </li>
             <li>[=Process the `scope` member=] passing |json|, |manifest|, and
             |manifest URL|.
             </li>