Throughout evolution, our brain has evolved into 3 main parts:
1) Lizard brain: Known as "toddler" brain or "caveman" brain located in the back of our brain, which is in charge of our survival. Its key job is to make sure we don't die. Lizard brain is our survival brain. It occupies only 10% of our brain volume, however 90% of our thoughts are formed in our Lizard brain. These thoughts are unconscious.
2) Mammalian brain: Its main function is in management of our "emotions" and forming "memory".
3) Higher brain: Known as "human" brain or "parent" brain is responsible for our executive functions, such as planning, goal setting, learning and languages. The higher brain occupies 75% of our brain but only 10% of our thoughts are formed here. These thoughts are all conscious.