Liferay Portal folder structure and their contents

Folder	Details
Benchmarks	Contains the script for testing the performance of Liferay portal using a tool called Grinder
Classes	Contains the compiled class files.Not signficant
Definitations	Contains the DTD files for the various XML files that are used by the Liferay. All  previous version of files are also maintained for backward compatibility.The DTD files present insidethis folder are for following types of XML files          Liferay-display.xml          Liferay-friendly-url-routes.xml          Liferay-hook.xml          Liferay-layout-templates.xml          Liferay-look-and-feel.xml          Liferay-plugin-package.xml          Liferay-plugin-repository.xml          Liferay-portlet.xml          Liferay-portlet-app.xml          Liferay-resource-action-mapping.xml          Liferay-service-builder.xml          Liferay-social.xml           Liferay-theme-loader.xml           Liferay-workfloe-definitation.xml
Lib	Contains all the jar files required for development ,global and portal.To understand the difference between the these jar file read the Readme.txt file and versions.html file to know about the versions of each jar
nbProject	A folder created by NetBeans IDE.you can ignore this
Portal-client	Contains all generated webservices stubs that will be used by any client application inorder to make a SOAP based webservice call to Liferay.
Portal-impl	This contains the implementation classes of all portal and portlet functionalities
Portal-service	Contains mostly the files generated by the Service Builder
Portal-web	Contains all css,images,theme related files,JSP Files and taglib JSP for various portal features and portlets that come bundled with Liferay
Sql	Contains various migration scripts for migrating lIferay from one version to another  version.
Support tomact	To support tomcat class lodaing feature
Tools	Maven Putty Jalopy Selenium YUI Compressor Grinder
Util-bridges	Contains portlet connectors for various fameworks and technologies.Some of bridges are javascript,ruby and php
Util-java	Most commonly used classes
Util-taglib	Contains the tag handler files for thevarious taglibs that comes bundled with Liferay.

Reference cookbook