Android is a mobile phone operating system initially developed by Android Inc, later purchased by Google. Anyone can download the SDK (software development kit) and write applications for Android phones. One can download the sdk at http.developer.android.com/sdk/. The sdk will allow you to develop, test, profile and debug using the emulator and other included tools.
The Android SDK provides tools and APIs to begin developing
Google doesn’t screen developers or applications. Google doesn’t even take part of the profits.
Google formed a group of hardware, software, and telecommunication companies called the Open Handset Alliance with the goal of contributing to Android development.
To develop usind Android SDK, as per the Android guide, its much easier to develop apps using eclipse. The basic requirements to develop using android are, download latest version of Android SDK and install it, download latest version of JDK (only JRE is not enough) and latest version of eclipse IDE for Java developers. Once you installed ecplipse, install the Android Development Toolkit (ADT). For eclipse galileo, start eclipse go to Help -> install new software and
In the Available Software dialog, click Add….
In the Add Site dialog that appears, enter a name for the remote site (for example, “Android Plugin”) in the “Name” field.
In the “Location” field, enter this URL:https://dl-ssl.google.com/android/eclipse/
Note: If you have trouble acquiring the plugin, you can try using “http” in the URL, instead of “https” (https is preferred for security reasons).
Back in the Available Software view, you should now see “Developer Tools” added to the list. Select the checkbox next to Developer Tools, which will automatically select the nested tools Android DDMS and Android Development Tools. Click Next.
In the resulting Install Details dialog, the Android DDMS and Android Development Tools features are listed. Click Next to read and accept the license agreement and install any dependencies, then click Finish.