Drying is very simply the removal of water molecules through passive diffusion. With lower relative humidity, water will naturally move to a area with less concentration. If humidity is too high, the diffusive action is slowed down or prevented entirely due to the balance of attraction.
The obvious reason for drying is because, wet dank dont burn well. When we incinerate cannabis, we perform a chemical process of removing water molecules from their acidic compounds (decarboxylation). This allows THC and other acidic molecules to turn into its physcoactive properties. Without this process, cannabis would not have a physiological effect. This is why heating is required on edibles before consumption.
As for the methods of how we dry, this is for different reasons. If expectations were for only removing moisture, a simple microwave dry would do. However, our traditional slow dry technique helps for other aspects.
Several chemicals are left in the plants flowers and leaf matter. These chemicals can present a harsher or distasteful smoke. Drying slowly, allows natural metabolic processes to continue utilizing and removing these chemicals. For example, chrolophyll has a lot of magnesium, bacteria if allowed, breaks down these chemicals allowing for a more even burn and smoother smoke.
Another reason for a slow dry, is that it creates a better moisture uniformity which has a more predictable and relatively easier burn factor. Allowing for better control of the smoke process.
Curing is the same method compared to traditonal drying except that the process is extended over a much longer time. With it comes additional benefits. Curing allows further break down of chemicals and better moisture concentration which allows the ability to store produce over much longer periods compared to typical storage practices. There is also the potential for higher potency from the extended drying, how this process functions however is unclear. Although its said that decarboxylation is the reason, this process happens anyway during incineration, which makes no difference how much was decarbed prior to this process. However i personally believe the water concentration and uniformity is the reason for the perceived differences, allowing for a more predictable and controllable burn during inhalation. For the same reasons wet dank is not that potent, even when burned. Because it is more difficult to light and reduces the efficiency of the chemical transfer process.
Hope that helps
