There is no broad international consensus on what constitutes a PPP. Broadly, PPP refers to arrangements, typically medium to long term, between the public and private sectors whereby part of the services or works that fall under the responsibilities of the public sector are provided by the private sector, with clear agreement on shared objectives for delivery of public infrastructure and/ or public services.
An increasing number of countries are enshrining a definition of PPPs in their laws, each tailoring the definition to their institutional and legal particularities. ppp.worldbank.org/public-private-partnership/legislation-regulation/laws/ppp-and-concession-laws
In other countries specific sectors are carved out from the definition, particularly those sectors which are effectively regulated or where there is extensive private sector initiative, such as in Telecoms. In some countries arrangements involving more limited risk transfer such as management contracts are excluded from the definition for institutional reasons as the authorities prefer that they fall under traditional procurement processes for goods and services. For sample laws, go to ppp.worldbank.org/public-private-partnership/legislation-regulation/laws
For more information, please see ppp.worldbank.org/public-private-partnership/overview