These are places where the risk of damage from burning is such that burning should not take place. This applies to some Sensitive Areas.
Some areas are identified as fire-free in SSSI consents, in Natura Muirburn Plans, or as part of publicly funded schemes and agreements, such as Agri-environment schemes, Rural Development Contracts, or Management Agreements with Scottish Natural Heritage or Historic Environment Scotland. These areas MUST NOT be burnt.
It is good practice to identify a network of patches that are not burnt or cut. Some of these will be particular features, as identified in the sections above (for example: waterbody buffers, steep slopes, peat hags, historical features) but there should also be fire-free areas in all parts of the landscape.

Sphagnum with heather (Photo credit: The Heather Trust)