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<h1 itemprop="name" style="margin-bottom:0;">Welcome to the Android Open Source Project!</h1>

<p>Android is an open source software stack for a wide range of mobile devices
and a corresponding open source project led by Google. This site and the Android
Open Source Project (AOSP) repository offer the information and source code you
need to create custom variants of the Android stack, port devices and
accessories to the Android platform, and ensure your devices meet compatibility
requirements.</p>

<h2 align="center">Android 7.1 Updates Available</h2>

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  <h3>What's New</h3>

<h4>New Dalvik Bytecodes and Formats</h4>
<p>Dalvik now offers new <strong><a
href="{@docRoot}devices/tech/dalvik/dalvik-bytecode.html">bytecode formats 45cc
and 4rcc</a></strong> and placeholder opcodes for <strong><a
href="{@docRoot}devices/tech/dalvik/instruction-formats.html">invoke-polymorphic
and invoke-polymorphic/range</a></strong>, which are the first dex instructions
that use these new formats. In addition to a method_idx that gives the invoked
method, these instructions also provide a proto_idx that gives the (static)
type signature of the call site.</p>

<h4>Background App Compilation in A/B System Updates</h4>
<p>Examples for
<strong><a href="{@docRoot}devices/tech/dalvik/configure.html#other_odex">installing</a></strong> and
<strong><a href="{@docRoot}devices/tech/ota/ab_updates.html#configuration">configuring</a></strong>
<code>otapreopt_script</code> have been added to explain how to use this tool
for optimizing user apps so they are ready to run after the device reboots
during an A/B system update.</p>

<h4>February Android Security Bulletin</h4>
<p>The <strong><a href="{@docRoot}security/bulletin/2017-02-01.html">February
2017 Android Security Bulletin</a></strong> has been published along with links
to associated fixes. In addition, new
<strong><a href="{@docRoot}source/build-numbers.html#source-code-tags-and-builds">build
numbers</a></strong> have been published for Nexus 6 running Android 7.0 and
7.1.1 and also Pixel, Pixel XL, Pixel C, Nexus 5X, Nexus 6P, Nexus 9, and Nexus
Player running Android 7.1.1 to support the February Android security release.</p>

<h4>Android 7.1 CDD</h4>
<p>The <strong><a href="{@docRoot}compatibility/7.1/android-7.1-cdd.html">7.1
version</a></strong> of the <strong><a
href="{@docRoot}compatibility/cdd.html">Android Compatibility Definition
Document</a></strong> (CDD) has been published. See its <strong><a
href="https://android.googlesource.com/platform/compatibility/cdd/+log/nougat-mr1-dev/?pretty=full&no-merges">change
log</a></strong> for a summary of updates.</p>

<h4>Diagnosing Native Crashes</h4>
<p><strong><a
href="{@docRoot}devices/tech/debug/native-crash.html">Native crashes</a></strong>
are now described in detail, fully explaining the <strong><a
href="{@docRoot}devices/tech/debug/native-crash.html#crashtypes">types of
crashes</a></strong> expected and including the clues for finding them in
<code>debuggerd</code> output.</p>

<h4>CTS and CTS Verifier 7.0, 6.0, and 5.1</h4>
<p>Android Compatibility Test Suite (CTS) and CTS Verifier 7.0 R5, 6.0 R14, and
5.1 R15 are available for <strong><a
href="{@docRoot}compatibility/cts/downloads.html">download</a></strong>. These
releases contain test fixes and verify security patches up to the <strong><a
href="{@docRoot}security/bulletin/2016-12-01.html">December 2016 Public
Security Bulletin</a></strong>.</p>

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<h3>Getting Started</h3>
<a href="{@docRoot}source/index.html"><h4>Explore the Source</h4></a>
<p>Get the complete Android platform and modify and build it to suit your needs.
You can also
<strong><a href="https://android-review.googlesource.com/#/q/status:open">contribute
to</a></strong> the <strong><a href="https://android.googlesource.com/">AOSP
repository</a></strong> to make your changes available to everyone else in the
Android ecosystem.</p>

<a href="{@docRoot}source/index.html"><img border="0"
src="images/android_framework_small.png" alt="Android framework summary"
style="display:inline;float:right;margin:5px 10px;width:42%;height:42%"></a>

<a href="{@docRoot}devices/index.html"><h4>Port Android to Devices</h4></a>
<p>Get help porting the latest Android platform to create compelling devices for
your customers. Includes documentation for HAL interfaces and details on core
technologies such as Android runtime (ART) and over-the-air (OTA) updates.</p>

<a href="{@docRoot}security/index.html"><h4>Make Secure</h4></a>
<p>Follow these examples and instructions to harden your Android devices against
malicious attacks. Find out how the Android security program works and learn how
to implement the latest features.</p>

<a href="{@docRoot}compatibility/index.html"><h4>Get Compatible</h4></a>
<p>Being Android-compatible lets you offer custom features but still give users
and developers a consistent and standard experience across all Android-powered
devices. Android provides guidance and a test suite to verify your Android
compatibility.</p>

<a href="https://android.googlesource.com/platform/docs/source.android.com/">
<h4>Help this Site</h4></a>
<p>Use the <strong>Site Feedback</strong> button at the bottom of any page to
request content improvements or let us know about errors. To contribute your
own updates to the site or to view a complete list of site changes, use the AOSP
project
<strong><a href="https://android.googlesource.com/platform/docs/source.android.com/+log/master?no-merges">docs/source.android.com.</a></strong></p>
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