See: Description
The portal-impl (com.liferay.portal.impl) module API reference documentation describes Liferay core classes, and is primarily intended for understanding or contributing to Liferay. Many of the classes referenced in this documentation should not be referenced directly from applications. Please refer to the public API reference documentation when developing applications.
Please note that the learning paths and tutorials in the developer section of the Liferay Developer Network provide the best resources to guide you in consuming Liferay services and customizing Liferay. In addition, the Developer Network's community section provides community resources and explains how you can participate in the Liferay Community.