What is a facial serum and what is it for?

In recent years it has become the star product of many cosmetic firms, but do you really need one?
The 
facial serum (or serum) came into our lives a few years ago, but its growth has been exponential. 
There is no 
beauty brand 
that does not offer not one, but different types of serums: anti-aging, exfoliating, anti-blemish, illuminating ... But, perhaps you have not yet decided to use one, so with the help of two 
pharmacists we are going to tell you 
what is a facial serum and what is it for 
The facial serum (also known as serum) is a product that, as the 
pharmacist Marta Masi tells us , "is characterized by a high concentration of active principles , which are quickly absorbed and penetrate, which can reach deeper layers, so that we get short-term results . "
In general, serums have a light and fresh texture . 
Some have a more watery, fluid consistency, others more like gel or emulsion. 
It is a beauty product that should be applied to clean skin and before the usual 
cream . 
It is important that you keep one fundamental idea: 
serum is not a substitute for moisturizer, it is a supplement.
WHAT IS A FACIAL SERUM FOR?
The pharmacist María José Cejas Delgado, from Farmacia Europa , sums it up like this "our skin can improve if we include a cream and a serum with the same purpose or effect in our routine". 
That is, the facial serum is a complement to the treatment and is not mandatory or necessary, but if you want to achieve more visible effects in less time it can help you.
Also read You should start using vitamin c serum now
HOW IS IT USED?
The serum is the first step of the routine after cleansing. 
It can be used 
in the morning and in the evening. You can actually use a different product. 
For example, in the morning, experts recommend using an antioxidant vitamin C serum and in the evening treating it with a glycolic acid exfoliating serum. 
The pharmacist Marta Masi advises "to apply a small amount on the face, neck and décolleté, 
wait a few seconds and then apply the cream . It is not necessary to wait long, except if we use a serum with AHA (alpha hydroxy acids such as 
glycolic ) for the night, I advise waiting a half hour for the product to act ".