All components included in the product supply are developed with use of the message files. This mechanism allows to use the same components for interfaces on different languages. For example, a component for news displaying can be used for sites both in English or German.

For each component or component group is created a description file .description.php. This file contains description of the component control panel:

• names of adjusted parameters;
• formats of fields used for parameter values assignment;
• default values of some parameters;
• etc.

Also this file can contain rules or functions used for defining some necessary source data and values. For example, descriptions for the information blocks components are stored in the file: /bitrix/modules/iblock/install/templates/iblock/.description.php.

More detailed description of the visual components structure and work is given in the Components 2.0 training course.