* maintaining.texi (Branches): Add motivations for branching.

doc/emacs/ChangeLog

+2013-06-02  Xue Fuqiao  <xfq.free@gmail.com>
+
+	* maintaining.texi (Branches): Add motivations for branching.
+
 2013-06-01  Glenn Morris  <rgm@gnu.org>
 
 	* programs.texi (Semantic): Fix typo.

doc/emacs/maintaining.texi

@@ -1266,10 +1266,16 @@ bring them back at a later time).
 @cindex branch (version control)
 
   One use of version control is to support multiple independent lines
-of development, which are called @dfn{branches}.  Branches are used
-for maintaining separate ``stable'' and ``development'' versions of a
-program, and for developing unrelated features in isolation from one
-another.
+of development, which are called @dfn{branches}.  Branches allow for
+parts of software to be developed in parallel.  Large projects require
+many roles to be filled, including developers, build managers, and
+quality assurance personnel. Further, multiple releases on different
+operating system platforms may have to be maintained.  Branches allow
+contributors to isolate changes without destabilizing the codebase,
+for example, fixes for bugs, new features, and versions
+integration. These changes may be later merged (resynchronized) after
+testing.
+
 
   VC's support for branch operations is currently fairly limited.  For
 decentralized version control systems, it provides commands for