Planning authorities make decisions on planning applications according to three key factors:

1. National planning policy guidance
2. The policies in the local authority's development plan - this might be a Local Plan, a Unitary Development Plan or a new-style Local Development Plan
3. Other ‘material considerations’, such as the planning history of the site and any precedent which has been set by existing developments.

Decisions are made either by planning officers (under 'delegated powers') or by a planning committee made up of local councillors.

Planning applications can either be:

1. Approved: This means planning permission is granted and the applicant will receive a 'decision notice'. The decision notice usually includes a number of 'planning conditions', which are set by the authority to make sure the development proceeds without causing harm.
2. Refused: This means planning permission is not granted and the applicant will receive a refusal notice. The refusal notice should give reasons why the application has been refused.
3. Deferred: This means the planning committee has decided it wants to visit the site, or needs more information before coming to a decision. Usually, a deferred application will be considered at the next planning committee meeting.

If you want to find out more about why a particular decision has been made on a planning application, you can contact your local planning authority to ask for a copy of the planning officer's report. This will give a fuller explanation of the reasons why the decision was made.