Whether you are talking about haircare, skincare or make up, silicones are one of those ingredients that polorises the beauty community. People either have no issues with using products containing silicones or they hate them and won't use products that contain it.
The silicones commonly used in skincare are Dimethicone, also known as Polydimethylsiloxane, Methicone and Cyclomethicone. Dimethicone is used in moisturisers as a skin protector. It helps to protect the skin by keeping moisture in. It also helps to fill in wrinkles, fix uneven skin tone, reduce redness and acne scars which is why it's a popular ingredient in primers. Dimethicone is a non-comedogenic ingredient (it doesn't clog pores).
In haircare it's used to coat the hair, helps to detangle, get rid of frizz and make it soft and smooth. Silicone is what makes your hair feel smooth when you are washing it. Because silicone coats the hair shaft, any other products you use won't penetrate. You'll then get a build up of products. Use a clarifying shampoo once a week if your haircare contains silicones.
Silicone is cheap and makes your skin feel soft and silky. It creates a barrier between your skin and the make up you apply on top of it. It's unlikely the silicone will be absorbed into the body due to its molecular size, since it's large and weighty, which is why it creates the barrier. Normally you would find sweat and oils will ruin your make up, but the silicone helps to protect it.
There are concerns that using silicones stops our body from naturally removing sweat and toxins because of the barrier. Some people also find that silicones are irritating to the skin. Try to give your face a day or two silicone free to breathe.
If you're concerned about silicones, scan the ingredients. If the ingredient ends in "cone" or "siloxane" it's most likely a silicone.