Most people have either experienced or heard of dandruff at some point in their lives. Shedding dead skin cells (flakes) is a completely normal process. Skin cells regenerate about every four weeks. When this happens, the old dead skin cells are shed. In fact, you shed dead skin cells every day. This includes your scalp. Most of the time, you never even notice when you shed skin cells. However, if the skin cells on your scalp regenerate at a faster than normal rate, they can also shed in clumps of cells that are visible. This is called dandruff. A little-known fact is that there are two types of dandruff: oily and dry. Let's take a look at the differences between the two and when it is time to seek professional trichological treatment.