The process of developing the applications which can run on the android operating systems is called as the android development. Even though there are many developing environment but usually the applications are developed using the java programming language with the Android SDK (software development kit). The android operating system will support all the feature of the java 7 language and some features from the java 8 languageIf the developers want to target the applications in the older devices then the SDK will support the older versions of the android development platform. You can download the components of the development tools. You can perform testing if you want to compare the older and latest versions of the Android platforms after downloading them. All the applications of android are packaged in the format of .apk . The packages are stored in android OS folder and it is accessible only to the root users for security reasons.