In Android, visual components are called Views . The resources for an Android project are stored in the /res folder of your project hierarchy, which includes layout, values, and a series of drawable sub-folders. The ADT plug-in interprets these resources to provide design-time access to them through the R variable. Dalvik Debug Monitoring Service (DDMS) : Use to monitor and control the services or processes of emulators. Android Debug Bridge (ADB) : A driver which provides link to virtual to physical devices. Logcat : Used to view the processes of android logging system. Android Asset Packaging Tool (AAPT) : Used to generate .apk file.