A common misconception is that dry and dehydrated skin are the same thing, which isn't the case!
Dry skin refers to the oil content in your skin which is in relation to your skin type. Your skin type is what you are born with, or the genetic make up of your skin. Being a dry skin means the oil glands in your skin do not produce enough oil. (Or the sebaceous glands to be technical).
Dehydrated skin refers to the water content in your skin. Which is a skin condition, not a skin type. A skin condition can refer to the affect the environment has or your skin, or your diet or any sort of lifestyle choices you make day to day that effect the hydration, or water content in your skin.
All humans are basically made of water, we're basically just cucumbers with more complicated emotions. And every single one of us can benefit from increasing hydration in our skin care routines and life.
A natural thing that dehydrated skin does, is produce more oil to compensate for the lack of water in the skin. Resulting in break outs, congestion and oily appearance to the skin.
If you are a cute face, who feels like they get both dry and oily... chances are you're most likely Oily/dehydrated and should increase the hydrating products in your skincare routine (and drink butt loads more water babe!)
I know that this is a common misconception, as I fell victim to it in the past. I used a lot of products not meant for my skin type because I thought I was both oily and dry... but in reality I was just a VERY OILY, dehydrated skin.
A general rule of thumb - if ever in doubt increase your hydration. It's always a good place to start.