Android (operating system)

Android (of english android / æn ˌ drɔjd / from Greek android humanoid, android ') is both an operating system and a software platform for mobile devices such as smartphones, mobile phones, netbooks, and tablet computers, which by the Open Handset Alliance (founded by Google ) is developed. The basis is the Linux kernel. In Android is free software, and open source is developed. Android had a smartphone operating system in the second quarter of 2013 announced a global market share of 79.3 percent after 68.1 percent in the second quarter of 2012, 52.5 percent in the third quarter of 2011 and 25.5 percent in the third quarter of 2010. In April 2013 Eric Schmidt, Executive Chairman of Google, that a day and a half million new Android devices are activated. This is almost three times as many as in July 2011. Since April 2013, the number of reactivations, however, seems to be stagnating. By September 2013, one billion Android devices have been activated worldwide.

Android includes a Linux kernel, but it is not a traditional Linux distribution, as they are known for desktop and server. Partly were basic features that you would expect from a Unix-like system, greatly changed.

  • 8.1 ports to other smartphones
  • 8.2 ports for x86/AMD64-Plattform
  • 8.3 Known derivatives
  • 9.1 Remote access to equipment
  • 9.2 openness
  • 9.3 Control by Google
  • 9.4 transmitting private data
  • 9.5 Malware
  • 9.6 Check for updates


In summer 2005, Google bought the company, founded in autumn 2003 by Andy Rubin Android, was from the very little more is known than that it developed software for mobile phones and location-based services primarily treated. Originally Android was exclusively for the control of digital cameras gedacht.Am November 5, 2007, Google announced known, together with 33 other members of the Open Handset Alliance to develop a mobile phone operating system called Android. Since October 21, 2008 Android is officially available.

As the first device with Android operating system came on 22 October 2008, the HTC Dream under the name T -Mobile G1 in the United States to market. Could already that this first device on the Global Positioning System (GPS) access and equipped with motion sensors, belonged to the concept of Android. There are now a large number of different devices from various manufacturers on which Android is preinstalled. Since January 2010, brings Google with the Nexus series products and even Android devices on the market. These are manufactured by different hardware partners, which also put in their own devices on Android. The software however, comes directly from Google and will be delivered without the usual manufacturer essay. Owner of a Nexus smartphones and tablets may be pleased usually on a relatively large number and fleet updates.

Interface and Operation

The user controls Android using various navigation buttons so-called. These consist "back" from ( go to previous activity), " Home" ( opens the start screen) and " Recent Applications" ( allows you to quickly switch back and forth between simultaneously running apps ). Prior to Android 4.0, and some manufacturers, there are also "Menu " or "Search ". Samsung sat a long time in its devices on the menu instead of multitasking button, and split this also from the position forth with the back button. Only in more recent models, the recommended Google button is used.

A distinction is made between software and hardware keys. The former are located on the display, the latter as physical buttons on the device itself. Advantage of virtual keys is that they are rotated or hidden when needed and thus can share precious space on the display. The full screen mode only works from version 4.4. Prior to it is possible only in videos, to hide the navigation bar.

The start screen, also known as home screen, used primarily for launching apps. Hence the English name " Launcher" comes (English " to launch " = start ). Unlike Apple's iOS are not necessarily all app shortcuts on one of the sides of the home screen, but this can be found in the App Drawer, which is provided with a tab, then find to Android 1.6 with a button at the bottom. This is adjacent to four major applications in the App dock that is visible on all sides. At the top of a Google search bar is always displayed, which can be in a special Launcher Google also started simply by speaking the words " Ok Google" and whose voice input is activated. Between the dock and search bar can be divided into a grid drop links ( to apps, bookmarks, contacts, etc. ), or widgets. These are usually somewhat larger displays general data, such as weather, time / date, dates, or even a calculator.

A big advantage of Android, the adaptability plays a role especially in the home screen. This allows developers to incorporate into their programs widgets that can put on the home screen of the user. In addition, alternative launcher apps with more settings or a different concept can also be downloaded. When pressing the Home button, you can select to which is to be used as the default application for the home screen of apps. Other parts of the system can be replaced, for example, the keyboard or the default browser.

Another feature of the operating system is the notification bar at the top of the screen. Each app can even create a notification when certain events occur, such as when a new mail, an appointment, or download operation of a newly installed app. If the bar is closed, the user will see top left for each notification an appropriate symbol. The right side also informed mainly with symbols via Bluetooth connection, ring mode, wireless connection, field strength, and data connection or airplane mode, battery level and time ( left to right). Notifications can be permanent, then they can not be removed by wiping as usual, but go by itself, if a certain condition is met ( for example, the notification " USB debugging " when the unit is connected to a computer ). There are also expandable notifications that show by down- drag other buttons, such as "Reply", "Forward" or "Delete" an e -mail, or in the audio playback a larger cover, the album name and Rewind button.

To open the Quick Settings or "Quick Settings", there are two possibilities: either by a two -finger gesture from top to bottom in a closed bar, or by using a button in the upper right corner with a normal open bar. The open menu consists of three columns of tiles that contain different information: user contact with picture (used in multi-user devices also used when to log off ), brightness (for pressure appears the brightness control ), Einstellungsshortcut, WLAN-/Bluetooth-/Standort- status ( short press will open corresponding settings menu, long press switches on or off ), battery (top tap leads to the battery settings ) and flight mode ( pressure switches on or off). Some tiles only appear in certain conditions, such as screen sharing, if appropriate screens are in range only.

Many manufacturers of Android devices install their own essays manufacturers like HTC Sense, Samsung 's TouchWiz UI with the Xperia and Sony's UI. These change the design of the surface dramatically, the basic structure remains mostly the same. Called The popular devices with pure Android, also called " Vanilla Android " or "stock Android ", the Nexus devices which have arisen from Google in close cooperation with a normal Android manufacturers and and long supplied directly fast with updates from the internet giants are. A similar status have so-called Google Play editions of already existing devices that are shipped with stock Android instead of the manufacturer surface. These updates come true again by the manufacturers themselves, but usually appear quite quickly.


The architecture of Android built initially on the 2.6 Linux kernel, Android 4.x from a kernel of the 3.x series will be used. He is responsible for memory management, process management, and provides the interface for playback of multimedia and network communications dar. He also is the hardware abstraction layer for the rest of the software and provides the device drivers for the system.

Other important elements are the based on the architecture developed by Sun Microsystems Java virtual machine Dalvik technology and the associated Android Java class libraries. The contents of the class library are strongly oriented towards the functionality of the Java Standard Edition. The free reimplementation of the Java Standard Edition Apache Harmony has been used as a basis. The runtime environment of Android is based on the Dalvik virtual machine, developed by Google employee Dan Bornstein virtual machine. The Dalvik VM is similar functionally normal Java VM, both lead so-called byte code. One of the main differences is the underlying virtual processor architecture. The Java VM is based on a pushdown automata; Dalvik VM on the other hand is a register machine. Due to the differing processor architecture, the compilations normal Java compilers are not suitable for the Dalvik VM, but Google was able to draw on the existing Java development tools.

Most modern compilers generate intermediate code as pushdown automata code. This intermediate code makes it possible to abstract from the processor architecture of the target platform, the programming language part is separated from the specific processor architecture. Since the processor model of pushdown automata is particularly simple, it is usually used for the intermediate language translator. Most real processors are today but register machines, such as the x86 and ARM processors. Register architectures are often more efficient because it does the CPU have their own very quickly accessible memory cells - the register - features. Dalvik is responsible for converting the pushdown automaton code in the register machine code at compile time already anticipated. The tool is used for dx, "dx " represents Dalvik cross assembler.

Applications for Androidplattform are usually written in Java, but grab this in speed-critical areas to numerous in C or C native libraries written to. The catalog includes codecs for media playback and a web browser based on WebKit, a database ( SQLite) and an OpenGL based 3D graphics library.

To develop your own programs for android, you need a recent Java SDK, and in addition, the Android SDK. First, the written in Java source code is translated to a normal Java compiler and then adjusted by a cross- assembler for the Dalvik VM. For this reason, programs can be created in principle with any Java development environment. The completed application must be in a. Apk package (English " Android Package" ) are packaged, then it can be installed on an application store or directly on the device via the package manager.

The framework relies on strong modularity. Thus, all components of the system are generally equal (except the virtual machine and the underlying core system ) and can be changed anytime. So it is for example possible to create your own application for creating text messages or to dial numbers and replace the existing application with it.

A further application development and Portierungsweg beyond Java provides the SDL library for SDL and native C code. Over a small java -based Wrappercodeanteil the use of native code is made possible via the JNI. In order for the porting of existing SDL applications on Android is relatively easy to, such as in Jagged Alliance 2 port.

Since Android does not include the full extent of the GNU libraries by default or non- standard compliant implements, and has its own window system, porting existing Linux applications or libraries is difficult.

Android EGL used as interface between the window system and OpenGL ES and OpenVG.

Availability of sources

Android is a free software. The largest part of the platform is under the Apache license - Exceptions are the Linux kernel, which is distributed under the GPL 2, and individual pre-installed applications from Google, whose source code is not available. The source code of exclusively for tablets written and initially available only for selected devices manufacturer version 3 was also released by Google with the publication of the sources of version 4.


Since version 1.5 support all versions of the version number to the English name of a dessert whose first letter is in ascending order respectively in the alphabet.

All versions up to version 2.3.x " Gingerbread " were intended only for smartphones, but were also used in navigation and other devices. With version 3 is dubbed "Honeycomb" was a purely for tablets provided by Google operating system. The separation between the two classes of devices was repealed with "Ice Cream Sandwich ", which is provided from the ground up for both systems.

Because the tablet market grew more and more and Google " Honeycomb" published quite late, brought some manufacturers tablets on the market that ran contrary to Google's recommendations under " Gingerbread ". Conversely wanted to prevent the "Honeycomb " version is used on smartphones, which is why the source code was not published until late Google.

For each version of Android designed Google / the OHA an Android mascot with each belonging to the version of dessert. This can be viewed from version 2.3 by successive touches on the Android version in the system settings.

Existing software

In Google Play Store (formerly Android Market), there are 800,000 applications (as of January 2013). So Google Play Store now has a larger app offer than the previously leading app provider Apple. In the SDK, a number of applications, including a Web browser, the card application Google Maps, SMS, e- mail and address book management, a music program, a camera and gallery application and a set of API demo applications also are included.

Developed software can be offered from the developers at Google Play. Can sell you them there but only if you are resident in certain states, are listed among others Germany, Austria and Switzerland. Free software makes up about 69 percent.

Addition Play Google developers and end-users are also a number of other markets and platforms for Android software open; However, some supposedly independent turn reference Google Play.

Google retains some control over Android software. Only licensed Android distributions may use Google's own ( closed source ) applications like Gmail or Google Maps and access to the Google Play Store for other applications. Different Tablets use an unlicensed Android 4 and do not have permission to access the Google Play Store. Also it is not possible applications from the Google Play on a non- Android system download (eg a normal PC ) to then install them via USB to an Android device. Some software manufacturers offer but their applications in alternative app stores or directly as an installation file; this can be downloaded in any way and then install it on your Android device.


Since version 4.0 (Ice Cream Sandwich) operating system has a high degree of accessibility. The required software is already installed and can theoretically be activated independently by a blind man. Here, Android has the advantage that speech ( screen reader ) and screen magnification can be used in parallel. Support for braille displays offers Android since version 4.1 and the extension Braille baking.

Dissemination and success

In the first quarter of 2010, more Android phones than iPhones were sold in the United States for the first time. The market share of new units was the period examined for Google 28 percent as opposed to 21 percent at Apple.

Worldwide in 2010 were sold with 67.2 million for the first time more Android smartphones than BlackBerry devices ( 47.5 million ) and iPhones ( 46.6 million ) after 2009 or 5 million Android devices to 25 million iPhones (iOS ) or, according to Gartner, Inc. were 6.8 million to 24.9 million.

In April 2013 Google said that 1.5 million Android devices activated per day. A total of 900 million devices have been activated with the Android operating system (as of May 2013). On September 3, 2013 Sundar Pichai announced that to date, a billion devices have been activated. The decision by Google to provide its operating system available for free use by manufacturers of terminal devices is popular.

This decision also led to a strong fragmentation. According to an assessment made by companies Staircase in May 2012 examination under Android smartphone users, which was conducted over a period of half a year, 3997 a total of 599 different devices from manufacturers could be counted. However, the result of so-called Custom Roms is, that is non-original manufacturer-provided operating programs, somewhat distorted.

In the third quarter of 2013, Android achieved a market share of 81 %, making it the most widely installed operating system on new smartphones sold.

From all supported versions of Android version " Jelly Bean" ( Android 4.1-4.3 ) currently applies to 61.4 % as the most common.

2013, some 870 million Android devices were sold worldwide in 2014 will Garter about 1.1 billion expected. This Android was in two years ago, Windows (330 or 360 million units ), the most widely installed operating system on the device classes PC, Smartphone and Tablet time.


Since the sources of Android are freely available and speak no legal reasons to the contrary, it can be ported to almost every computer sufficiently powerful relatively simple. If a platform is supported by the Linux kernel, there is a good possibility that a port of Android can succeed. There are ports for smartphones that were originally shipped with another operating system. Other projects to port Android for a standard desktop computer. Many of these porting projects are driven by a worldwide community of developers. The Open Handset Alliance supports these projects with its own Porting Instructions.

Ports to other smartphones

Ports for the x86/AMD64-Plattform

Known derivatives


Remote access to devices

Google has the ability, if the Google Apps are installed, delete software without prompting the user and install. About a possible permanent connections to Google's servers could applications via remote access without the action, but with knowledge of the user, deleted and installed ( status message ). If Google drops a paid software, the customer shall receive back the purchase price. In June 2010, Google has for the first time applications on the devices of users deleted by a remote access after security experts had introduced a malicious program in the then Android Market, to draw attention to the lack of controls.


Although Android is free software, located in most standard delivered Android devices proprietary software from Google, such as the mapping software Google Maps. Even the most tightly integrated Google online services such as Google or Gmail are proprietary. Moreover, there is criticism of a development model that shows little openness to outside developers. In an EU-funded study from July 2011 various free software projects have been evaluated with an Open Governance Index, Android fell here by a wide margin on the last place, while projects such as MeeGo, Linux or Eclipse scored points because of their more open development process. Android has been referred to as "the least open mobile open source project" ( " the least open open source project for mobile phones "). Also, the first version of Android designed only behind closed doors and then released. The source code of Android 3.0 for tablets was also initially not made public and was not available until after the release of Android 4.0.

Since Android systems are not fully free software and Google Play allows the use of proprietary binary software, Richard Stallman and the Free Software Foundation Android are very critical and recommend the use of alternatives.

Control by Google

Because of Google's control of the brand and of the operating system Android device manufacturers rely on the cooperation with Google. This control shall Google have used in the past, among other things, to prevent equipment manufacturers use the location services from Skyhook Wireless instead of Google's own as well as to prevent Acer introduces devices with the competing operating system Aliyun.

Transmitting private data

Many applications require access to private data like contacts, location, telephone number and can forward this also. You can deny access to it, in this case the application is not installed. One app can be withdrawn even after installation specific permissions, which is often possible without root privileges. Possibly. it is then no longer executable. There are numerous apps known that request significantly more privileges and transmit data than would be required for their function.

Sometimes also ask unnecessary pre-installed applications from many private data. This can hardly prevent and pre-installed applications can not be removed without root privileges. Even pure trading apps entirely without function for the user were delivered pre-installed.

Applications have permission to internet access to upload files to the SD card on the internet.


With its ever-increasing penetration rate Android is becoming increasingly interesting for malware writers. In particular, the ability to install unverified third-party apps ( to the consent of the user is required), increases the risk. Google checks since the beginning of 2012 all apps in the Play Store automatically. Therefore, it is when you install apps only from there, relatively safe; However, there are also known cases of malware spreading via the Play Store. Further security is provided by the default in Android Sandboxing: All apps run in a separate virtual machine. Requested permissions of the apps are displayed and require the consent of the user.

Various security vendors provide security apps with more or less good results available. These manufacturers are also what make the often noisy and media attention on a "threat" attentive to market their products. Another type of threat are available in the latest equipment NFC short-range radio was from a security specialist at the hacker conference Black Hat 2012 demonstrated.

On November 27, 2013, the Berlin security firm Curesec published a vulnerability that allows a malicious app all lockscreen disabled mechanisms that have been activated by the user. It also provides an app available that illustrates this vulnerability. Curesec called as affected Android versions initially only version 4.3, now the versions are 4.0 to 4.3 as affected. The security issue has been closed with the version 4.4.

Check for updates

Android smartphones are often sold with an older version of the operating system. There are usually between customers and manufacturers no support contracts, whereby no contractual obligations for the manufacturer made ​​to provide updates. Also, he is obliged by buying the device only to its proper operating on delivery - an Update obligation under the purchase contract does not exist. That Updates " late " or not even appear, is severely criticized by customers.

At the developer conference Google I / O in May 2011, Google pointed out, however, that many manufacturers were to provide for each new device for at least 18 months after the release of updates to the latest Android version. However, there are already reports that manufacturers break this commitment. At the Google I / O in June 2012, Google released a Platform Development Kit, which enables manufacturers early to port new versions of Android on their hardware.

Due to the openness of Android source and the Linux kernel development team provide free unofficial updates, so-called Custom -Roms, ready for some devices.

Not affected by the late or non-existent update are the devices of the Google Nexus series (eg Google Nexus 5, 4 Nexus, Galaxy Nexus, Nexus 7, Nexus 10). These receive the latest updates from Android with only short delays. They are so long to date until the 18-month time period of update support ends.

Patent litigation

Google is accused of using Android to hurt a large number of patents of other companies. Consequently, it was since 2009 the world to a series of legal disputes with manufacturers. Microsoft has completed with many of these manufacturers license agreements and earned thereby estimated 3 to 12.50 U.S. dollars per sold Android device, a total of about 500 million U.S. dollars in fiscal year 2012.

In addition, Google was sued in August 2010 from Oracle, because supposedly patent and trademark rights in the context of Java were injured. The dispute could Google decide in the first instance itself.