The National Planning Policy Framework (NPPF) sets out the government’s main planning policies for England and how they are expected to be applied. The NPPF is supported by National Planning Practice Guidance which provides further context. The PPG is only available online and you can sign up for email alerts to be informed of any changes. It was most recently updated in 2019 - https://www.gov.uk/government/publications/national-planning-policy-framework--2
The overall aim of national policy is to ensure the planning system contributes to the achievement of sustainable development. Achieving sustainable development means that the planning system has three overarching objectives (economic, social and environmental). The NPPF requires planning policies and decisions to play an active role in guiding development towards sustainable solutions, but in doing so, should take account of local circumstances, to ensure new development reflects the character, needs and opportunities of each area.
In addition to the NPPF there are other national planning policies on: sustainable drainage systems; parking; starter homes; the housing delivery test; waste; traveller sites; and school development.
The NPPF does not contain specific policies for nationally significant infrastructure projects. These are determined in accordance with the decision making framework in the Planning Act 2008 (as amended) and relevant national policy statements for major infrastructure, as well as any other matters that are relevant.
Government policy may also be altered by a Written Ministerial Statement.