This Practice Note explains when planning permission is required in Scotland under the Town and Country Planning (Scotland) Act 1997 (TCP(S)A 1997) by analysing the statutory meaning of development. It covers operational development, including building operations, demolition, engineering, mining and other operations involving physical change to land, and identifies key exclusions such as internal works, non-material external alterations, certain infrastructure works, incidental residential uses, agriculture and forestry. It examines material change of use, focusing on planning impact, character and intensification of use, and the concept of the planning unit. It also outlines changes of use not constituting development and explains the role of lawful development certificates in confirming lawful existing or proposed development. It is part of a collection of guidance on planning in Scotland, see: Planning for property lawyers in Scotland—collection. Meaning of development Pursuant to TCP(S)A 1997, s 28, planning permission is required for ‘the carrying out of any development of land’. Development is defined in TCP(S)A 1997, s 26: • the carrying out of building, engineering, mining