Android categorizes device screens using two general properties: size and density. You should expect that your app will be installed on devices with screens that range in both size and density. As such, you should include some alternative resources that optimize your app’s appearance for different screen sizes and densities.
- There are four generalized sizes: small, normal, large, xlarge
- And four generalized densities: low (ldpi), medium (mdpi), high (hdpi), extra high (xhdpi)
To declare different layouts and bitmaps you'd like to use for different screens, you must place these alternative resources in separate directories, similar to how you do for different language strings.