Essence/Serum
I have always thought these 'essence/serum' products are gimmicks to lure women to buy more stuff.
I know better now after speaking to a professional esthetician. They are basically water based liquid to replenish our skin with H2O as well as other nourishment. In this modern times, we are so busy with our lives, be it career or family, that we just don't drink enough water. Soda and coffee don't count. As we all know, dehydration is never good.
So instead of trying to drink 8 glasses of water a day, which can be quite challenging when you are stressed out from work and the last thing on your mind is drinking water, you can use these essence/serum to help rehydrate your skin. They are usually very light and watery and it is absorbed quickly into your skin (from what I have tried).
I have started using these products and my skin has improved tremendously. However, it doesn't mean that I don't get pimples. My face can be smooth as a baby's bottom and I will have a big pimple sitting on my cheek. So what I am trying to say is that, based on my experience, rehydrating your skin with essence/serum will make your skin supple and radiant but it doesn't do anything to pimples.
I have tried a few already, mostly samples and I'll review them soon.