Hospital information systems (HIS), also referred to as clinical information systems (CIS), are comprehensive and integrated information systems designed to manage the clinical aspects and business administrative functions of healthcare organizations. The scope of HIS varies, but essentially these systems comprise one or more software applications with clinical specialty extensions, administrative functions and ancillary support, or a large variety of sub-systems in medical specialties such as the laboratory information and radiology information systems. Historically, HIS were used as remote data processing applications to handle routine operations such as accounting, billing, payroll, drug inventory, computer-assisted diagnostics and clinical instrumentation. Available to internal users only, these applications were designed based on ad-hoc demands and were often unable to interact with existing legacy systems. Frequently, users printed out the results generated by one system, and manually entered them into another system. Since most HIS were used to perform only specific operating tasks, users relied on paper trails for documentation and records for backup information.