Honey is simply a super saturation of sugar; this simply means it has a higher concentration of dissolved sugar in its liquid component than what is dissolvable under normal conditions. Actually, honey at some point turns into crystalline sugar. There are terms used for this process like crystallization, granulation, solidification, and sugared. This is a very natural process.
The type of flower the honey bee visited when gathering the blossom's nectar is what makes the honey crystallize. The speed at which the honey solidifies is solely determined by the floral source. Some raw honeys can remain in their liquid form for a very long time. Other honeys can become solids after a few weeks. This is as a result of the level of stability of the sugar crystal in the nectar. Remember the sugar crystals we always made when we were grade school kids, we left the sugar water to boil to the point of evaporation with a string in it that aided the formation of crystals. This is quite similar to what happens in honey.
This does nothing to the quality of the honey. The taste and nutritional value still remain unchanged after the honey has solidified. You may discover you prefer the solidified honey to the liquid form!! You can spread it on your bread or toast and it won't drip off. You can easily scoop it from the jar and add it to your favorite hot drink without any runoffs. You can easily turn it back to its liquid and pourable state by warming the containing jar very gently in warm water, but avoid using hot water.
P.S. You don't need to store your honey in the refrigerator because it speeds up the crystallization process.