It was placed by Gartner in the Magic Quadrant among the leaders of the "Horizontal portal", the only open source.
It consists of three parts: a kernel (Liferay Portal), which serves as a basis for applications and content, a Content Management System (Liferay CMS) and a suite of applications for collaboration and social networks (Liferay Collaboration).
It is based on a service-oriented architecture (SOA), which makes it possible to develop applications, called Portlets, starting from existing web services. These portlets are web applications written in Java, designed to be inserted into a portal, defined in the JSR-168 and JSR-286 standards.
Portlets are components that define the markup of the individual application within a portal page. They are managed by a container portlet and a portal server, which is responsible for serving the pages to the browser. Together, these two systems constitute the portal infrastructure necessary for application deployment.
Regarding the database persistence, Liferay has a code-generator, called "service builder", which allows to automatically generate entities, sql scripts and database interface classes.
source wikipedia