A language catalog is a set of text strings in a particular language, created as key name/value pairs. Applications can use these catalogs to fill in the names of menu items, buttons, and other elements of a user interface, for example. The use of different language catalogs, then, can support an application's internationalization: for example, letting a user decide what language to use for installing and running the application.
There are two main advantages of using a language catalog in a separate file, rather than having these strings embedded in the application:
In addition, because the language catalogs are in XML format, you can easily read and edit the files in any text editor.
Implementing language catalog functionality requires two parts:
.cat) file, which contains the name/value pairs in the desired languages. See Creating a Language Catalog File for information on requirements for a language catalog file's structure.