Formal planning instruments and procedures in spatial planning are regulated by public construction and planning law. They are characterised by defined procedural steps and participation structures. The catalogue of topics, to which planning statements have to be made, is given. A specific planning perimeter often requires comprehensive content-related statements. The planning result of formal planning creates a binding effect and therefore also planning security, depending on the instrument not only for authorities, but also for citizens.
Informal planning instruments and procedures do not underlie the fixed procedures of public planning law, so that they can be designed flexibly and matched to the conditions according to the occasion, the topic or the constellation of stakeholders.Informal planning is not regulated (in its accuracy) as much formal planning. Informal planning is indispensable for the preparation of formal planning as well as for many others.