"PEAR primarily targets the "Architecture Domain": code that can be re-used in many applications, but targets a particular architecture (namely, Web applications). The majority of the "packages" provided by PEAR solve specific problems that are commonly encountered by those building Web apps, irrespective of the type site being built. For example, PEAR::Validate provides a library of common validation routines, helping you to validate anything from a URL (very important if you want to prevent XSS exploits) to International Bank Account Numbers (IBAN)." - Goran Zec