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+<?xml version="1.0" encoding="latin1" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+  <header>
+    <copyright>
+      <year>2001</year><year>2009</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      The contents of this file are subject to the Erlang Public License,
+      Version 1.1, (the "License"); you may not use this file except in
+      compliance with the License. You should have received a copy of the
+      Erlang Public License along with this software. If not, it can be
+      retrieved online at http://www.erlang.org/.
+    
+      Software distributed under the License is distributed on an "AS IS"
+      basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+      the License for the specific language governing rights and limitations
+      under the License.
+    
+    </legalnotice>
+
+    <title>Introduction</title>
+    <prepared>Bjorn Gustavsson</prepared>
+    <docno></docno>
+    <date>2007-11-21</date>
+    <rev></rev>
+    <file>introduction.xml</file>
+  </header>
+
+  <section>
+    <title>Purpose</title>
+
+    <quote><p>Premature optimization is the root of all evil. -- D.E. Knuth</p></quote>
+
+    <p>Efficient code can be well-structured and clean code, based on
+    on a sound overall architecture and sound algorithms.
+    Efficient code can be highly implementation-code that bypasses
+    documented interfaces and takes advantage of obscure quirks in
+    the current implementation.</p>
+    
+    <p>Ideally, your code should only contain the first kind of efficient
+    code. If that turns out to be too slow, you should profile the application
+    to find out where the performance bottlenecks are and optimize only the
+    bottlenecks. Other code should stay as clean as possible.</p>
+
+    <p>Fortunately, compiler and run-time optimizations introduced in
+    R12B makes it easier to write code that is both clean and
+    efficient. For instance, the ugly workarounds needed in R11B and earlier
+    releases to get the most speed out of binary pattern matching are
+    no longer necessary. In fact, the ugly code is slower
+    than the clean code (because the clean code has become faster, not
+    because the uglier code has become slower).</p>
+    
+    <p>This Efficiency Guide cannot really learn you how to write efficient
+    code. It can give you a few pointers about what to avoid and what to use,
+    and some understanding of how certain language features are implemented.
+    We have generally not included general tips about optimization that will
+    work in any language, such as moving common calculations out of loops.</p>
+  </section>
+
+  <section>
+    <title>Prerequisites</title>
+    <p>It is assumed that the reader is familiar with the Erlang
+      programming language and concepts of OTP.</p>
+  </section>
+</chapter>
+