The term "permitted development" describes some kinds of small-scale constructions or alterations to the existing structures or land that can be carried out without obtaining planning permission. The rights regarding the permitted developments are called permitted development rights. These rights, which are subject to restrictions and circumstances, are bestowed by the government through legislation. The scope of permitted development rights varies according to the planning laws of the nation or area, but generally speaking, they include things like:

Small Extensions: Adding small parts to the existing buildings within certain size constraints.
Loft Conversions: Transforming loft areas into livable rooms, provided that certain requirements are met, such as volume and roof slope.
Changes of Use: Transforming a structure or piece of land into a residential home within specified categories without obtaining planning permission; an example of this would be turning a commercial property into a residential home.
Outbuildings: Build certain outbuilding types—like garages, garden rooms, or sheds—while adhering to regulations on size and other details.
Alterations to Buildings: Making certain changes to the buildings, for instance, installing solar panels or replacing windows, without requiring planning permission.
Demolition: Certain structures may be demolished without obtaining planning approval, subject to restrictions and requirements.

Use the following URL links for more information on permitted development and permitted development rights.

https://www.legislation.gov.uk/uksi/2015/596/schedule/2/made

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/830643/190910_Tech_Guide_for_publishing.pdf

https://www.planningportal.co.uk/info/200187/your_responsibilities/37/planning_permission/2

What is permitted development?