The PEAR package contains: * the PEAR installer, for creating, distributing and installing packages * the PEAR_Exception PHP5 error handling mechanism * the PEAR_ErrorStack advanced error handling mechanism * the PEAR_Error error handling mechanism * the OS_Guess class for retrieving info about the OS where PHP is running on * the System class for quick handling of common operations with files and directories * the PEAR base class Features in a nutshell: * full support for channels * pre-download dependency validation * new package.xml 2.0 format allows tremendous flexibility while maintaining BC * support for optional dependency groups and limited support for sub-packaging * robust dependency support * full dependency validation on uninstall * remote install for hosts with only ftp access - no more problems with restricted host installation * full support for mirroring * support for bundling several packages into a single tarball * support for static dependencies on a url-based package * support for custom file roles and installation tasks