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+++ b/documentation/ref-manual/technical-details.xml
@@ -1031,6 +1031,41 @@
                 building goes on for a given recipe.
             </para>
         </section>
+
+        <section id='patching-dev-environment'>
+            <title>Patching</title>
+
+            <para>
+                Once source code is fetched and unpacked, BitBake locates
+                patch files and applies them to the source files:
+                <imagedata fileref="figures/patching.png" align="center" width="6in" depth="5in" />
+            </para>
+
+            <para>
+                The <filename>do_patch</filename> task processes recipes by
+                using the
+                <link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
+                variable to locate applicable patch files, which by default
+                are <filename>*.patch</filename> or
+                <filename>*.diff</filename> files, or any file if
+                "apply=yes" is specified for the file in
+                <filename>SRC_URI</filename>.
+            </para>
+
+            <para>
+                BitBake finds and applies multiple patches for a single recipe
+                in the order in which it finds the patches.
+                Patches are applied to the recipe's source files located in the
+                <link linkend='var-S'><filename>S</filename></link> directory.
+            </para>
+
+            <para>
+                For more information on how the source directories are
+                created, see the
+                "<link linkend='source-fetching-dev-environment'>Source Fetching</link>"
+                section.
+            </para>
+        </section>
     </section>
 </section>