By default , an activity is themed to the default Android theme. However , there been a push in recent year to adopt a new theme known as Material . The Material theme has a much more modern and clean look to it. There are two versions of the Material theme available to Android developers : Material Light and Material Dark , Either of these themes can be applied from the AndroidManifest.xml To apply one of the Material themes to an activity , simply modify the <Application> element in the AndroidManifest.xml file by changing the default android:theme attribute. (Please be sure to change all instances of "com.android" to whatever package name your project is using.) <?xml version="1.0" encoding="utf-8"?> <manifest xmls:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" package="com.android.activity101"> <application ...