Assurance services

Assurance services have been defined by the American Institute of Certified Public Accountants (AICPA) as 'Independent Professional Services that improve information quality or its context'. Such services are very broad and could include assessments of internet security and quality of health facilities.
The important point is that these services (also known as attestation services) require independence. They require independence because they typically are performed in order to report certain findings to a third party.