We have all been through moments, when we feel a strong sense of knowing about a situation, a person or a life event, your gut senses it, and more often than not it comes true. These are intuitions.
And we often wonder as to where they come from? Recently I experienced something similar which made me pursue it a bit.
From what I could gather, human responses work on 2 different planes, mind based consciousness (reactive domain) and heart based consciousness(HBC). 
When your thoughts and responses and reactions are synchronised with HBC, and if you are in an elevated state of vibrations, the thoughts that originate, come from knowing of the digested knowledge about that situation or person or event. What that means is, you have absorbed some facts, some behaviour, some patterns about that person over a period of time (without even being aware), and when your thoughts come from HBC and this absorbed knowledge and your elevated vibrational energy, they are intuitive. These are intuitions. 