PFI was introduced in order to engage the private sector in the design, build, finance and operation of public infrastructure, with the aim of delivering good quality and well maintained assets that provided value for money for the taxpayer. It has been used across a broad range of sectors. Over 700 projects have reached financial close, securing private sector investment of around £55 billion. Since its introduction, PFI has remained a small but important part of the Government's overall investment in public infrastructure and services.