PEAR stands for
PHP Extension and Application Repository.
To learn more about the PEAR library
click here
If you are beginner, the following link will help you tread with the library usage
PEAR Manual
Installation instructions clearly walks through the steps for PEAR configuration. There may be cases where you may want to use PEAR libraries for specific projects only in which case you can install PEAR library for that specific purpose. To use it in projects, PEAR path should be set in
php.ini settings or should be included in the project configuration's physical path.