ERP systems are now commonly used in large businesses and vendors are targeting SMEs. This will have many consequences that must be addressed by understanding the history and evolution of ERP systems and their architectures. The success of ERP adoption will depend on the ability of legacy systems to integrate additional modules like CRM, SCM, and internet applications. ERP software consists of integrated modules that support common business functions like finance, accounting, production planning, and HR. It has evolved from MRP systems focused on manufacturing to integrate enterprise-wide processes. Major ERP modules include manufacturing, logistics, finance, sales and distribution, and human resources.