Internationalization (i18n for short) is the process of adding a framework to support different national languages to your program. Localization (l10n) occurs when you use that framework to customize the program for each language. National language support is only going to get more important over time as internet usage grows in countries like China, India, and Brazil. Luckily GWT provides full and flexible support as of version 1.1.10 of the toolkit. Even if your application is not intended for a global audience, it pays to put all your human readable text in one place. You can more easily spell check your messages and ensure consistency between them if they’re all in the same file. It also lets non-programmers change the messages to correct grammatical errors or trademark usages without having to modify the code. The standard Java way to accomplish this is through resource bundles and property files. GWT lets you use these familiar concepts in your web applications as well.
Internationalization (I18n) – GWT