Only some Manuka Honey has the special UMF activity. UMF stands for 'Unique Manuka Factor', a measure of the unique type of activity which is naturally present at varying levels in honey made from the nectar of the Manuka bush (Leptospermum scoparium),native to New Zealand.
The mark UMF is followed by a number that indicates the strength of the UMF activity in a batch of UMF Manuka Honey. The higher the UMF rating, the more potent the product.
For example, a jar of UMF 10+ Manuka Honey has twice the activity of UMF 5+ Active Manuka Honey.