RTL (Right-to-left) support is an essential part in planning for i18n and L10n. Unlike English language which is written from left to right, many languages like Arabic, Japanese, Hebrew, etc. are written from right to left. To appeal to a more global audience, it is a good idea to plan your layouts to support these language from the very beginning of the project, so that adding localization is easier later on.

RTL support can be enabled in an Android app by adding the supportsRtl tag in the AndroidManifest, like so :

<application
    ...
    android:supportsRtl="true"
    ...>
...
</application>