Introverted intuition is the intuition that acts in an introverted and thus, subjective manner. Introverted intuition is a function that is often described as hard to explain, due to its highly inward and intangible nature. The introverted intuition type has the ability to 'thread' multiple sources of phenomena into a certain view or vision. This is contrary to its opposite, extraverted sensation, which sees things as they comes and in a very concrete manner.
The lack of this extraverted sensation can often make the Ni type a very dogged character, ignoring what is apparent and focusing on their synthesised worldview. Unlike its introverted irrational counterpart, introverted sensation, introverted intuition looks not to indulge in a meticulous cataloging of physical experiences and recalling them when the user perceives similarity in their subjective experiences of current reality (since Si doesn't objectively experience reality unlike Se) but always looks for future implications of the observable reality and how one chain of event leads to another. It always goes beyond the concrete data where Si does not.
Where Ne perceives breadth, Ni compensates this with depth in its perceptions.
Ni operates together with Se, forming the Se-Ni axis. It observes the physical properties of objects vividly (Se) and perceives possibilities in the inner world (Ni), where these perceptions are subjective and diluted by the subject's biases hence, these associations are personal to the subject and in no way represent reality, but an abstract interpretation.
This gives higher Ni users intense focus and an air of mysticism. Ni dominants always go beyond the objective physical concreteness of objects and find their interpretation more interesting and delicious. Ni-Se can be termed as conjecturing.