UMF or the Unique Manuka Factor is a type of a scale that can help you find out whether the Manuka honey you are eating and buying actually contains the essential powers that real Manuka honey would have. The Unique Manuka Factor grading scale is the only way for a person to tell whether the Manuka honey they are eating is real and also how helpful it is, as well as what grade of Manuka honey it is.
The Unique Manuka Factor starts at 0+ UMF and goes on until 30+ UMF, with each rating having a certain meaning. 0+ UMF and 5+ UMF Manuka honey is the least cooked or heated honey and has little to no therapeutic power to it and is mostly just used as a breakfast honey, the 10+ UMF and 15+ UMF range is where the most useful type lies. The jars that have a 10+ UMF or 15+ UMF rating are the ones that have the best therapeutic power to them and even supply a lot of daily supplements to the person consuming it. On the more extreme end anything over 20+ UMF is Manuka honey that has been a little cooked to get a higher rating on the scale.
Now the reason this scale exists is to differentiate real Manuka honey from fake Manuka honey. Anything that has one of the UMF ratings is genuine Manuka regardless of the rating. This is done because a lot of companies have begun selling fake Manuka honey simply because people want to avail the health benefits that this honey can provide. This is why not everyone is allowed to use this seal and an international body called the Unique Manuka Factor Honey Association was created to test and give these ratings. http://healingmanuka.com has all the necessary information about this.