The Evaluation of Android API levels

In the search of knowledge in android, I had this worrying question on my mind for a while. That is what are the significant highlights in android API levels and how could they impact to my development. So I search through the internet and found valuable information on android site. But it takes some time to read all these changes so I thought I need to summarize those changes so one can get a bird view on this.(Actually I have listed what I think as important. So I didn’t listed all the changes. Go to this link and you will find all the changes.)

Platform version	API Level	New Additions
Android 1.0	1	Begin of a new era
Android 1.1	2	•      For T-Mobile G1
Android 1.5	3 Cupcake	•      SlidingDrawer / HorizontalScrollView •      OnScreen soft keyboard •      Speech recognition via RecognizerIntent •      LocationManager - Applications can get location change updates via Intent •      WebView - Touch start/end/move/cancel DOM event support •      Redesigned Sensor Manager APIs •      GLSurfaceView - convenience framework for creating OpenGL  applications •      Broadcast Intent for app update install succeeded - for smoother app  upgrade experience
Android 1.6	4 Donut	•      New android.view.animation •      Quick Search Box •      New gesture API •      New android.speech.tts •      New SmsManager •      New DisplayMetrics •      New <supports-screens> •      New <uses-feature>  •      Battery usage indicator •      updated OpenCore 2 media engine
Android 2.0	5 Eclair	•      ANT support •      New APIs for sync adapters •      Bluetooth Support •      Live Wallpapers
Android 2.2.x	8 Froyo	•      android:installLocation install app in external storage •      New android:backupAgent •      generalized backup service on Cloud •      New OpenGL ES 2.0 •      Dalvik JIT compiler •      Portable hotspot •      V8 JavaScript engine •      New UI modes "car mode" and "night mode"  •      New ScaleGestureDetector •      The layout attribute fill_parent is renamed to match_parent •      android.permission.SET_TIME — allows an application to set the system time.
Android 2.3.2 Android 2.3.1 Android 2.3	9 Gingerbread	•      SIP based VOIP android.net.sip (Internet Calling) •      NFC (Near Field Communication) •      gyroscope, rotation vector, linear acceleration, gravity, and barometer •      Multiple cameras support by Camera API  •      New DownloadManager system service •      New  system facility StrictMode •      Support for overscroll •      Text selection controls •      Notification text and icon styles(New TextAppearance.StatusBar.EventContent, TextAppearance.StatusBar.EventContent.Title,TextAppearance.StatusBar.Icon, and TextAppearance.StatusBar.Title) •      supports extra-large screen sizes •      New AlarmClock •      New  Criteria class •      New  StorageManager
Android 2.3.4 Android 2.3.3	10 Gingerbread	•      NFC upgrades
Android 3.0.x	11 Honeycomb	•      Introducing Fragments •      An application will crash if it does not call through to the super implementation of its Activity.onPause() method. •      Action bar instead of tittle bar •      Support for multi core architecture •      Loader: A framework component that facilitates asynchronous loading of data in combination with UI components to dynamically load data without blocking the main thread. See the Loaders developer guide •      Drag and drop functionality •      HTTP live streaming •      support for Media/Picture Transfer Protocol (MTP/PTP) over USB •      System clipboard •      JsonReader and JsonWriter •      Media sync from SD card
Android 3.1.x	12 Honeycomb	•      Exposes an API to its built-in RTP (Real-time Transport Protocol) stack •      homescreen widgets resizeable •      New  LruCache class •      USB APIs •      MTP/PTP APIs
Android 3.2	13 Honeycomb	•      New resource qualifiers(sw320dp, sw720dp, w720dp, h1024dp) •      tabs are typically presented in the UI using the new ActionBar.newTab()
Android 4.0, 4.0.1, 4.0.2	14 Ice Cream Sandwitch	•      Social APIs in contacts provider •      New user profile •      Contact usage feedback •      New calendar API to change data which are stored in Calendar Provider •      New Voicemail Provider •      Camera class now includes APIs for detecting faces and controlling focus and metering areas •      Android Beam •      Wi-Fi peer-to-peer (P2P) connections •      Explore-by-touch mode •      New  VpnService •      New  view group GridLayout •      New  view TextureView •      Navigation bar •      Updated V8 JavaScript compiler
Android 4.0.3, 4.0.4	15 Ice Cream Sandwitch	•      social stream API in contacts provider
Android 4.1, 4.1.1	16 Jelly bean	•      Isolated services android:isolatedProcess="true"  •      New getMyMemoryState(ActivityManager.RunningAppProcessInfo) •      New intent protocol to directly launch the live wallpaper •      App stack navigation using android:parentActivityName •      The AudioEffect class now supports additional audio pre-processing types when capturing audio •      Android Beam™ now supports large payload transfers over Bluetooth •      The new InputManager class allows you to query the set of input devices •      Extends vsync timing across all drawing and animation done by the Android framework •      Expandable Notification •      Lights out and full screen mode
Android 4.2, 4.2.2	17 Jelly bean	•      Daydream  •      Allows users to add app widgets to the lock screen •      Multiple user spaces on shareable devices such as tablets •      Right-to-left (RTL) UIs and reading direction, such as Arabic and Hebrew •      Nested fragments. Nested fragments are only supported when added to a fragment dynamically •      Renderscript Compute which is the first computation platform ported to run directly on a mobile device GPU •      Wireless display solution that complies with the Miracast •      HDR camera scene mode
Android 4.3	18 Jelly bean	•      Behavioral changes( load an intent in a different user profile) •      Java interfaces and native support for OpenGL ES 3.0. •      Mipmapping for drawables. •      ViewOverlay class •      Optical background layouts for 9 patch images. •      New rotationAnimation field in WindowManager while screen rotation •      New service class, NotificationListenerService  •      The Trace class •      Android sandbox reinforced with SELinux •      Keystore provider and APIs that allow applications to create exclusive-use keys
Android 4.4	19 KitKat	•      WebView support for new HTML5 features, and support for remote debugging •      New android.print framework •      The Telephony content provider (the "SMS Provider") allows apps to read and write SMS and MMS messages on the device •      Host card emulation (emulates NFC cards for data exchange) •      New NFC reader mode •      Rate the current track from the remote controller •      New android.transition framework facilitate animations between different states of your user interface •      Built-in step sensors •      System bars partially translucent with new themes, Theme.Holo.NoActionBar.TranslucentDecorand Theme.Holo.Light.NoActionBar.TranslucentDecor. •      In WebView, apps targeting earlier versions will have JS URLs evaluated directly and any result of the evaluation will not replace the current page content. Apps targetting KITKAT or later that load a JS URL will have the result of that URL replace the content of the current page •      New API, ActivityManager.isLowRamDevice(), lets you tune your app's behavior to match the device's memory configuration. •      A new storage access framework •      Full screen immersive mode •      A new tool called procstats helps you analyze the memory resources your app uses
Android 4.4W		•      For Android Wear(Android watch)
Android 5.0	21 Lollipop	•      Material Design •      Screen capturing and screen sharing capabilities with android.media.projection APIs •      Java interfaces and native support for OpenGL ES 3.1. •      New android.hardware.camera2 API to facilitate fine-grain photo capture and image processing •      Act as a Bluetooth LE peripheral device •      improvements in battery life.(project volta) •      new JobScheduler API that lets you optimize battery life by defining jobs for the system to run asynchronously at a later time or under specified conditions (such as when the device is charging) •      New screen pinning API •      Render PDF document pages into bitmap images for printing by using the new PdfRenderer class •      New ART runtime to support a mix of ahead-of-time (AOT), just-in-time (JIT), and interpreted code •      platform support for 64-bit architectures(Nexus 9's NVIDIA Tegra K1) •      New  tilt detector and a heart rate sensor
Android 5.1	22 Lollipop	•      Multiple SIM card support
Android 6.0	23 M	•      App linking •      Automatic full data backup and restore for apps. •      Authenticate users by using fingerprint scans on supported devices •      Support for the Hotspot 2.0 Release 1 spec on Nexus 6 and Nexus 9 devices

So This only a small summary on Android API levels. Hope this may help to someone. :-)