The S-N dichotomy is our ‘input’ scale - ie how we each take in and process information. As Jung suggests:
The Sensation and Intuition…are perceptive functions, they make us aware of what is happening, but do not interpret or evaluate it.
interpretation and evaluation are the purpose of the Judging functions: Thinking and Feeling.
Sensing types prefer the known, the factual, the actual, the concrete. They are present-oriented and prefer a grounded approach taking in information that has practical application and may see concepts and theoretical models as a bit airy-fairy. Intuitive types prefer seeing possibilities, shapes and patterns. They like to ‘see around corners’ and will prefer information that has general principles and scope for change. They are future-oriented and like juggling possibilities and see factual material as a little dry.
Jung saw this scale as the process involved in becoming aware of something, ie how we take information in, process and access it and identified two kinds of perception: Sensation and Intuition. Sensing is a taking in information in a tangible, concrete way, focusing, according to Jung:
...on the perception of actualities...These are the fact-minded men, in whom intellectual judgement, feeling, and intuition are driven into the background by the paramount importance of actual facts.
Intuiting is a process of taking in information in concepts and visually, around future possibilities and where, according to Jung:
...actual reality counts only in so far as it seems to harbour possibilities which then become the supreme motivating force, regardless of the way things actually are in the present.
Sensing and Intuiting can both be carried out in either the outer, extraverted world or in the inner, introverted world depending upon our own orientation on the E-I scale.