Dimethicone is the most popular silicone. It makes the skin softer and forms a film adding smooth and silky feeling. This film not only improves how the skin feels but also works as a protective barrier. It also improves the visual appearance of your skin by filling small wrinkles. That's why some people think dimethicone removes wrinkles. Actually, it does not. It's just a visual effect.
One of the most important characteristics of this component is that it helps to spread other ingredients evenly on the surface to provide good coverage. It's very important because you want all your skin cells to receive an equal proportion of the components.
Dimethicone is considered as safe, but remember that it is rather difficult to wash off! This may lead to clogged pores and acne if you use it too often and don't wash off quite well.